Remove unecessary git checkout command from README

The command is not needed, because the specified branch is already the
default branch on GitHub so will be checked out by clone automatically.

PiperOrigin-RevId: 430910549

README.md

@@ -96,13 +96,11 @@ 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
 changes, or if you want to use the main branch.
 
-First, clone the repository into a local directory and checkout the desired
-branch:
+First, clone the repository into a local directory:
 
 ```sh
 git clone https://github.com/androidx/media.git
 cd media
-git checkout main
 ```
 
 Next, add the following to your project's `settings.gradle` file, replacing