Tweak release note

RELEASENOTES.md

@@ -2,8 +2,11 @@
 
 ### 2.11.4 (2020-04-08) ###
 
-* Add optional automatic `WifiLock` handling to `SimpleExoPlayer`
-  ([#6914](https://github.com/google/ExoPlayer/issues/6914)).
+* Add `SimpleExoPlayer.setWakeMode` to allow automatic `WifiLock` and `WakeLock`
+  handling ([#6914](https://github.com/google/ExoPlayer/issues/6914)). To use
+  this feature, you must add the
+  [WAKE_LOCK](https://developer.android.com/reference/android/Manifest.permission.html#WAKE_LOCK)
+  permission to your application's manifest file.
 * Text:
   * Catch and log exceptions in `TextRenderer` rather than re-throwing. This
     allows playback to continue even if subtitle decoding fails