Merge pull request #342 from nkubala/support

Document official support level from Google

Author: nkubala

README.md

@@ -16,6 +16,8 @@ container-diff is a tool for analyzing and comparing container images. container
 
 These analyses can be performed on a single image, or a diff can be performed on two images to compare. The tool can help users better understand what is changing inside their images, and give them a better look at what their images contain.
 
+**NOTE: container-diff is a Google project, but is not currently being officially supported by Google and is in maintenance mode. However, contributions are still welcome and encouraged!**
+
 ## Installation
 
 ### macOS