Add deprecating note (#641)

Author: alexandergoncharov-zz

README.md

@@ -10,6 +10,7 @@ This plugin provides client-side integration for the [CodePush service](https://
 
 * [How does it work?](#how-does-it-work)
 * [Supported Cordova Platforms](#supported-cordova-platforms)
+* [Deprecating old versions](#deprecating-old-versions)
 * [Getting Started](#getting-started)
 * [Plugin Usage](#plugin-usage)
 * [Releasing Updates](#releasing-updates)
@@ -49,6 +50,12 @@ cordova platform update android
 cordova platform update ios
 ```
 
+## Deprecating old versions
+
+Since CodePush is migrating to a new service all versions of cordova-plugin-code-push lower than **[1.12.0](https://github.com/microsoft/cordova-plugin-code-push/releases/tag/v1.12.0)** will not work in the nearest future.
+
+You can find more information in our [documentation](https://github.com/microsoft/code-push/blob/master/migration-notice.md).
+
 ## Getting Started
 
 Once you've followed the general-purpose ["getting started"](https://docs.microsoft.com/en-us/appcenter/distribution/codepush/) instructions for setting up your CodePush account, you can start CodePush-ifying your Cordova app by running the following command from within your app's root directory: