Add release notes for issues fixed by preloading migration

PiperOrigin-RevId: 312080838

RELEASENOTES.md

@@ -193,13 +193,25 @@
     ([#7234](https://github.com/google/ExoPlayer/issues/7234)).
 *   AV1 extension: Add a heuristic to determine the default number of threads
     used for AV1 playback using the extension.
-*   IMA extension: Upgrade to IMA SDK version 3.18.2, and migrate to new
-    preloading APIs ([#6429](https://github.com/google/ExoPlayer/issues/6429)).
 *   IMA extension:
     *   Upgrade to IMA SDK version 3.19.0, and migrate to new preloading APIs
-        ([#6429](https://github.com/google/ExoPlayer/issues/6429)).
+        ([#6429](https://github.com/google/ExoPlayer/issues/6429)). This fixes
+        several issues involving preloading and handling of ad loading error
+        cases: ([#4140](https://github.com/google/ExoPlayer/issues/4140),
+        [#5006](https://github.com/google/ExoPlayer/issues/5006),
+        [#6030](https://github.com/google/ExoPlayer/issues/6030),
+        [#6097](https://github.com/google/ExoPlayer/issues/6097),
+        [#6425](https://github.com/google/ExoPlayer/issues/6425),
+        [#6967](https://github.com/google/ExoPlayer/issues/6967),
+        [#7041](https://github.com/google/ExoPlayer/issues/7041),
+        [#7161](https://github.com/google/ExoPlayer/issues/7161),
+        [#7212](https://github.com/google/ExoPlayer/issues/7212),
+        [#7340](https://github.com/google/ExoPlayer/issues/7340)).
     *   Add support for timing out ad preloading, to avoid playback getting
-        stuck if an ad group unexpectedly fails to load.
+        stuck if an ad group unexpectedly fails to load
+        ([#5444](https://github.com/google/ExoPlayer/issues/5444),
+        [#5966](https://github.com/google/ExoPlayer/issues/5966)
+        [#7002](https://github.com/google/ExoPlayer/issues/7002)).
 *   OkHttp extension: Upgrade OkHttp dependency to 3.12.11.
 *   Cronet extension: Default to using the Cronet implementation in Google Play
     Services rather than Cronet Embedded. This allows Cronet to be used with a