Update media3 docs with details of new release branch

PiperOrigin-RevId: 430911179
(cherry picked from commit 7d389361)

README.md

@@ -94,7 +94,7 @@ to prevent build errors.
 
 
 Cloning the repository and depending on the modules locally is required when
 Cloning the repository and depending on the modules locally is required when
 using some libraries. It's also a suitable approach if you want to make local
 using some libraries. It's also a suitable approach if you want to make local
-changes, or if you want to use the main branch.
+changes, or if you want to use the `main` branch.
 
 
 First, clone the repository into a local directory:
 First, clone the repository into a local directory:
 
 
@@ -127,7 +127,7 @@ implementation project(':media-lib-ui')
 Development work happens on the `main` branch. Pull requests should normally be
 Development work happens on the `main` branch. Pull requests should normally be
 made to this branch.
 made to this branch.
 
 
-We plan to add a release branch soon.
+The `release` branch holds the most recent stable release.
 
 
 #### Using Android Studio
 #### Using Android Studio