Fix release notes

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=201374393

RELEASENOTES.md

@@ -14,6 +14,8 @@
   ([#4315](https://github.com/google/ExoPlayer/issues/4315)).
 * Fix missing whitespace in CEA-608
   ([#3906](https://github.com/google/ExoPlayer/issues/3906)).
+* Fix crash downloading HLS media playlists
+  ([#4396](https://github.com/google/ExoPlayer/issues/4396)).
 * Set `METADATA_KEY_TITLE` on media descriptions
   ([#4292](https://github.com/google/ExoPlayer/issues/4292)).
 * Allow apps to register custom MIME types
@@ -78,7 +80,7 @@
     periods are created, released and being read from.
   * Support live stream clipping with `ClippingMediaSource`.
   * Allow setting tags for all media sources in their factories. The tag of the
-    current window can be retrieved with `ExoPlayer.getCurrentTag`.
+    current window can be retrieved with `Player.getCurrentTag`.
 * UI components:
   * Add support for displaying error messages and a buffering spinner in
     `PlayerView`.