Fix the version numbers for a revert from EE to CE

doc/update/11.6-ce-to-ee.md

@@ -77,13 +77,13 @@ sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production
 
 If all items are green, then congratulations upgrade complete!
 
-## Things went south? Revert to previous version (Community Edition 11.5)
+## Things went south? Revert to previous version (Community Edition 11.6)
 
 ### 1. Revert the code to the previous version
 
 ```bash
 cd /home/git/gitlab
-sudo -u git -H git checkout 11-5-stable-ee
+sudo -u git -H git checkout 11-6-stable-ee
 ```
 
 ### 2. Restore from the backup