README updates for remaining ExoPlayer modules

PiperOrigin-RevId: 402287125

extensions/ima/README.md

-# ExoPlayer IMA extension
+# ExoPlayer IMA module
 
-The IMA extension is an [AdsLoader][] implementation wrapping the
-[Interactive Media Ads SDK for Android][IMA]. You can use it to insert ads
-alongside content.
+The ExoPlayer IMA module provides an [AdsLoader][] implementation wrapping the
+[Interactive Media Ads SDK for Android][IMA]. You can use it to insert ads into
+content played using ExoPlayer.
 
 [IMA]: https://developers.google.com/interactive-media-ads/docs/sdks/android/
 [AdsLoader]: https://exoplayer.dev/doc/reference/index.html?com/google/android/exoplayer2/source/ads/AdsLoader.html
@@ -25,12 +25,11 @@ locally. Instructions for doing this can be found in the [top level README][].
 
 ## Using the module
 
-To use the extension, follow the instructions on the
+To use the module, follow the instructions on the
 [Ad insertion page](https://exoplayer.dev/ad-insertion.html#declarative-ad-support)
 of the developer guide. The `AdsLoaderProvider` passed to the player's
 `DefaultMediaSourceFactory` should return an `ImaAdsLoader`. Note that the IMA
-extension only supports players which are accessed on the application's main
-thread.
+module only supports players that are accessed on the application's main thread.
 
 Resuming the player after entering the background requires some special
 handling when playing ads. The player and its media source are released on
@@ -46,8 +45,8 @@ position before preparing the new player instance. Finally, it is important to
 call `ImaAdsLoader.release()` when playback has finished and will not be
 resumed.
 
-You can try the IMA extension in the ExoPlayer demo app, which has test content
-in the "IMA sample ad tags" section of the sample chooser. The demo app's
+You can try the IMA module in the ExoPlayer demo app, which has test content in
+the "IMA sample ad tags" section of the sample chooser. The demo app's
 `PlayerActivity` also shows how to persist the `ImaAdsLoader` instance and the
 player position when backgrounded during ad playback.
 

extensions/workmanager/README.md

-# ExoPlayer WorkManager extension
+# ExoPlayer WorkManager module
 
-This extension provides a Scheduler implementation which uses [WorkManager][].
+This module provides a `Scheduler` implementation that uses [WorkManager][].
 
 [WorkManager]: https://developer.android.com/topic/libraries/architecture/workmanager.html
 
@@ -19,3 +19,10 @@ Alternatively, you can clone this GitHub project and depend on the module
 locally. Instructions for doing this can be found in the [top level README][].
 
 [top level README]: https://github.com/google/ExoPlayer/blob/release-v2/README.md
+
+## Links
+
+*   [Javadoc][]: Classes matching `com.google.android.exoplayer2.ext.workmanager.*`
+    belong to this module.
+
+[Javadoc]: https://exoplayer.dev/doc/reference/index.html

library/all/README.md

 # ExoPlayer full library
 
-An empty module that depends on all of the other library modules. Depending on
-the full library is equivalent to depending on all of the other library modules
-individually. See the [top level README][] for more information.
+An empty module that depends on all of the other ExoPlayer library modules.
+Depending on the full library is equivalent to depending on all of the other
+library modules individually. See the [top level README][] for more information.
 
 [top level README]: https://github.com/google/ExoPlayer/blob/release-v2/README.md
 

library/core/README.md

-# ExoPlayer core library module
+# ExoPlayer module
 
-The core of the ExoPlayer library.
+This module provides `ExoPlayer`, the `Player` implementation for local media
+playback on Android.
+
+## Getting the module
+
+The easiest way to get the module is to add it as a gradle dependency:
+
+```gradle
+implementation 'com.google.android.exoplayer:exoplayer-core:2.X.X'
+```
+
+where `2.X.X` is the version, which must match the version of the other media
+modules being used.
+
+Alternatively, you can clone this GitHub project and depend on the module
+locally. Instructions for doing this can be found in the [top level README][].
+
+[top level README]: https://github.com/google/ExoPlayer/blob/release-v2/README.md
+
+## Using the module
+
+The [developer guide](https://exoplayer.dev/hello-world.html) documents how to
+get started.
 
 ## Links