Link to new migration guide

Author: hramos

README.md

@@ -149,7 +149,7 @@ The full documentation for Parse Server is available in the [wiki](https://githu
 
 ## Migrating an Existing Parse App
 
-The hosted version of Parse will be fully retired on January 28th, 2017. If you are planning to migrate an app, you need to begin work as soon as possible. There are a few areas where Parse Server does not provide compatibility with the hosted version of Parse. Learn more in the [Migration guide](https://github.com/ParsePlatform/parse-server/wiki/Migrating-an-Existing-Parse-App).
+The hosted version of Parse will be fully retired on January 28th, 2017. If you are planning to migrate an app, you need to begin work as soon as possible. There are a few areas where Parse Server does not provide compatibility with the hosted version of Parse. Learn more in the [Migration guide](https://parse.com/migration).
 
 ## Configuration