Update documentation in README

Author: philipwalton

README.md

@@ -694,14 +694,15 @@ interface Metric {
   entries: (PerformanceEntry | LayoutShift | FirstInputPolyfillEntry | NavigationTimingPolyfillEntry)[];
 
   /**
-   * The type of navigation
+   * The type of navigation.
    *
-   * Navigation Timing API (or `undefined` if the browser doesn't
-   * support that API).
-   * For pages that are restored from the bfcache, this value will
-   * be 'back-forward-cache'.
-   * For pages that are restored after being discarded, this value will
-   * be 'restore'.
+   * This will be the value returned by the Navigation Timing API (or
+   * `undefined` if the browser doesn't support that API), with the following
+   * exceptions:
+   * - 'back-forward-cache': for pages that are restored from the bfcache.
+   * - 'prerender': for pages that were prerendered.
+   * - 'restore': for pages that were discarded by the browser and then
+   * restored by the user.
    */
   navigationType:  'navigate' | 'reload' | 'back-forward' | 'back-forward-cache' | 'prerender' | 'restore';
 }

src/types/base.ts

@@ -59,11 +59,15 @@ export interface Metric {
   entries: (PerformanceEntry | LayoutShift | FirstInputPolyfillEntry | NavigationTimingPolyfillEntry)[];
 
   /**
-   * The type of navigation
+   * The type of navigation.
    *
-   * Navigation Timing API (or `undefined` if the browser doesn't
-   * support that API). For pages that are restored from the bfcache, this
-   * value will be 'back-forward-cache'.
+   * This will be the value returned by the Navigation Timing API (or
+   * `undefined` if the browser doesn't support that API), with the following
+   * exceptions:
+   * - 'back-forward-cache': for pages that are restored from the bfcache.
+   * - 'prerender': for pages that were prerendered.
+   * - 'restore': for pages that were discarded by the browser and then
+   * restored by the user.
    */
   navigationType:  'navigate' | 'reload' | 'back-forward' | 'back-forward-cache' | 'prerender' | 'restore';
 }