Added notice that we're no longer using the changelog file

Author: tabacitu

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 All Notable changes to `Backpack Generators` will be documented in this file
 
+------------
+IMPORTANT
+------------
+
+Starting with version 3, the changelog is kept inside the Releases tab in our this repo's Github page. Please check https://github.com/Laravel-Backpack/Generators/releases
+
 ------------
 
 ## 2.0.7 - 2020-03-05