Note explicitly that GHE v2.0 is supported

Author: rtomayko

README.md

@@ -58,8 +58,12 @@ and growth over time.
 
 ##### GitHub Enterprise version requirements
 
-For online and incremental backup support, the GitHub Enterprise instance must
-be running version 11.10.342 or above.
+The backup utilities are fully supported under GitHub Enterprise 2.0 or
+greater.
+
+The previous release series (11.10.34x) is also supported but must meet minimum
+version requirements. For online and incremental backup support, the GitHub
+Enterprise instance must be running version 11.10.342 or above.
 
 Earlier versions are supported, but online and incremental backups are not
 supported. We strongly recommend upgrading to the latest release if you're