correct the javadoc of onRenderedFirstFrame in VideoListener

Issue: #7097
PiperOrigin-RevId: 301456951

library/core/src/main/java/com/google/android/exoplayer2/video/VideoListener.java

@@ -52,7 +52,7 @@ public interface VideoListener {
 
   /**
    * Called when a frame is rendered for the first time since setting the surface, and when a frame
-   * is rendered for the first time since a video track was selected.
+   * is rendered for the first time since the renderer was reset.
    */
   default void onRenderedFirstFrame() {}
 }