Update README.md for overrideAppVersion()

Author: Richard Hua

README.md

@@ -1105,6 +1105,8 @@ Because of this behavior, you can safely deploy updates to both the app store(s)
 
 - __(NSURL \*)bundleURLForResource:(NSString \*)resourceName withExtension:(NSString \*)resourceExtension__: Equivalent to the `bundleURLForResource:` method, but also allows customizing the extension used by the JS bundle that is looked for within the app binary. This is useful if you aren't naming this file `*.jsbundle` (which is the default convention).
 
+- __(void)overrideAppVersion:(NSString \*)appVersionOverride__ - Sets the version of the application's binary interface, which would otherwise default to the App Store version specified as the `CFBundleShortVersionString` in the `Info.plist`. This should be called a single time, before the bundle URL is loaded.
+
 - __(void)setDeploymentKey:(NSString \*)deploymentKey__ - Sets the deployment key that the app should use when querying for updates. This is a dynamic alternative to setting the deployment key in your `Info.plist` and/or specifying a deployment key in JS when calling `checkForUpdate` or `sync`.
 
 ### Java API Reference (Android)
@@ -1131,6 +1133,8 @@ Constructs the CodePush client runtime and represents the `ReactPackage` instanc
 
 - __getBundleUrl(String bundleName)__ - Returns the path to the most recent version of your app's JS bundle file, using the specified resource name (e.g. `index.android.bundle`). This method has the same resolution behavior as the Objective-C equivalent described above.
 
+- __overrideAppVersion(String appVersionOverride)__ - Sets the version of the application's binary interface, which would otherwise default to the Play Store version specified as the `versionName` in the `build.gradle`. This should be called a single time, before the CodePush instance is constructed.
+
 ## Example Apps / Starters
 
 The React Native community has graciously created some awesome open source apps that can serve as examples for developers that are getting started. The following is a list of OSS React Native apps that are also using CodePush, and can therefore be used to see how others are using the service: