Update README.md

Update the documentation to let people knwo they can even download runtimes also. The actual documentation doesn't add reference to that.

README.md

@@ -64,6 +64,8 @@ If that occurs, it means you need to select a version of Xcode. You can do this
 
 ## Usage
 
+### Install Xcode : 
+
 Install a specific version of Xcode using a command like one of these:
 
 ```sh
@@ -99,6 +101,20 @@ If you have [aria2](https://aria2.github.io) installed (it's available in Homebr
 
 Xcode will be installed to /Applications by default, but you can provide the path to a different directory with the `--directory` option or the `XCODES_DIRECTORY` environment variable. All of the xcodes commands support this option, like `select` and `uninstall`, so you can manage Xcode versions that aren't in /Applications. xcodes supports having all of your Xcode versions installed in _one_ directory, wherever that may be.
 
+### Install Runtimes : 
+
+Run this command line to display the available runtimes 
+
+```sh
+xcodes runtimes --include-betas
+```
+
+Install the wanted Runtime (ex. iOS 17.0-beta1)
+
+```sh
+xcodes runtimes install "iOS 17.0-beta1"
+```
+
 ### `.xcode-version`
 
 We recommend the creation of a `.xcode-version` file to explicitly declare and store the Xcode version to be used by your CI environment as well as your team.