chore: regenerate README (#1335)

This PR was generated using Autosynth. 🌈


<details><summary>Log from Synthtool</summary>

```
2021-08-06 11:33:38,296 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-spanner/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-08-06 11:33:39,698 synthtool [DEBUG] > Wrote metadata to .github/readme/synth.metadata/synth.metadata.

```
</details>

Full log will be available here:
https://source.cloud.google.com/results/invocations/71a87cb7-b8b9-4d6a-9ef8-2121670082f9/targets

- [ ] To automatically regenerate this PR, check this box. (May take up to 24 hours.)

Author: yoshi-automation

.github/readme/synth.metadata/synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-spanner.git",
-        "sha": "f54bb2823899f28c52ede162aec2f2c1ff429f6d"
+        "sha": "d0d3d213be7e0c03c3885eb4d96a4f55ac2fc2e2"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "3d32990b6f4b57be77455e3ca89e6e21cd0c06b3"
+        "sha": "df7fc1e3a6df4316920ab221431945cdf9aa7217"
       }
     }
   ]

README.md

@@ -245,18 +245,25 @@ Samples are in the [`samples/`](https://github.com/googleapis/java-spanner/tree/
 | Async Transaction Manager Example | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/AsyncTransactionManagerExample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/AsyncTransactionManagerExample.java) |
 | Batch Sample | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/BatchSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/BatchSample.java) |
 | Create Backup With Encryption Key | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/CreateBackupWithEncryptionKey.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/CreateBackupWithEncryptionKey.java) |
+| Create Database With Default Leader Sample | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/CreateDatabaseWithDefaultLeaderSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/CreateDatabaseWithDefaultLeaderSample.java) |
 | Create Database With Encryption Key | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/CreateDatabaseWithEncryptionKey.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/CreateDatabaseWithEncryptionKey.java) |
 | Create Database With Version Retention Period Sample | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/CreateDatabaseWithVersionRetentionPeriodSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/CreateDatabaseWithVersionRetentionPeriodSample.java) |
 | Create Instance Example | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/CreateInstanceExample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/CreateInstanceExample.java) |
 | Create Instance With Processing Units Example | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/CreateInstanceWithProcessingUnitsExample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/CreateInstanceWithProcessingUnitsExample.java) |
 | Custom Timeout And Retry Settings Example | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/CustomTimeoutAndRetrySettingsExample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/CustomTimeoutAndRetrySettingsExample.java) |
 | Get Commit Stats Sample | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/GetCommitStatsSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/GetCommitStatsSample.java) |
+| Get Database Ddl Sample | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/GetDatabaseDdlSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/GetDatabaseDdlSample.java) |
+| Get Instance Config Sample | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/GetInstanceConfigSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/GetInstanceConfigSample.java) |
+| List Databases Sample | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/ListDatabasesSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/ListDatabasesSample.java) |
+| List Instance Configs Sample | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/ListInstanceConfigsSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/ListInstanceConfigsSample.java) |
+| Query Information Schema Database Options Sample | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/QueryInformationSchemaDatabaseOptionsSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/QueryInformationSchemaDatabaseOptionsSample.java) |
 | Query With Numeric Parameter Sample | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/QueryWithNumericParameterSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/QueryWithNumericParameterSample.java) |
 | Quickstart Sample | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/QuickstartSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/QuickstartSample.java) |
 | Restore Backup With Encryption Key | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/RestoreBackupWithEncryptionKey.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/RestoreBackupWithEncryptionKey.java) |
 | Spanner Sample | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/SpannerSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/SpannerSample.java) |
 | Statement Timeout Example | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/StatementTimeoutExample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/StatementTimeoutExample.java) |
 | Tracing Sample | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/TracingSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/TracingSample.java) |
+| Update Database With Default Leader Sample | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/UpdateDatabaseWithDefaultLeaderSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/UpdateDatabaseWithDefaultLeaderSample.java) |
 | Update Numeric Data Sample | [source code](https://github.com/googleapis/java-spanner/blob/master/samples/snippets/src/main/java/com/example/spanner/UpdateNumericDataSample.java) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/java-spanner&page=editor&open_in_editor=samples/snippets/src/main/java/com/example/spanner/UpdateNumericDataSample.java) |