Added note about support for 4.x branch. (#148)

Author: Nyholm

README.md

@@ -14,6 +14,10 @@ into Symfony. It integrates seamlessly with the Symfony profiler. You can
 check number of queries executed by each provider, total execution time
 and geocoding results.
 
+> **Note**: You are browsing the docs for the 5.x release. Our older 4.x docs are 
+[found here](https://github.com/geocoder-php/BazingaGeocoderBundle/tree/4.x). Version
+4.x will be activly supported until 2018-02-25. 
+
 ![Example
 Toolbar](Resources/doc/toolbar.png)