doc/README.md: note simpler symbol links

Document that links to symbols in the standard library can be
written as "[foo]", without the actual link.

For #64169.

Change-Id: I9d8a33e85df70037320a169d55a2bb4a8a981ebf
Reviewed-on: https://go-review.googlesource.com/c/go/+/577915
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
diff --git a/doc/README.md b/doc/README.md
index 3bb8412..666e096 100644
--- a/doc/README.md
+++ b/doc/README.md
@@ -27,9 +27,9 @@
 
 Use the following forms in your markdown:
 
-	[`http.Request`](/pkg/net/http#Request)         # symbol documentation
-	[#12345](/issue/12345)                          # GitHub issues
-	[CL 6789](/cl/6789)                             # Gerrit changelists
+	[http.Request]                     # symbol documentation; auto-linked as in Go doc strings
+	[#12345](/issue/12345)             # GitHub issues
+	[CL 6789](/cl/6789)                # Gerrit changelists
 
 ## For the release team