add exclude_list documentation to distributions/cc7

docs/distributions/cc7.md

@@ -15,7 +15,8 @@ Apart from the obvious, the script also supports:
 * Building CERN rpms (if they are placed in the neccessary `incoming` directories)
 * Automatic rebuild of the openafs kmod for main and centosplus kernels
 * Ability to pause the release by populating a `/mnt/data2/home/build/bin/.freeze` file
-* Administrator email notifications in the event of a failure or if there are no new packages for a daily run
+* Ability to exclude packages from promotion to production by populating the `/mnt/data2/home/build/bin/exclude_list` file
+* Administrator email notifications in the event of a failure, no new packages, or if only src/debug packages were released
 
 !!! danger ""
     Nobody should need to follow the below instructions for daily testing/production updates, however the information is still provided if at all needed.