Add comment about client_acl_blacklist

conf/master

@@ -150,12 +150,18 @@
 #
 
 # Blacklist any of the following users or modules
-#client_acl_blacklist:
-#  users:
-#    - root
-#    - '^(?!sudo_).*$'   #  all non sudo users
-#  modules:
-#    - cmd
+#
+# This example would blacklist all non sudo users, including root from
+# running any commands. It would also blacklist any use of the "cmd"
+# module.
+# This is completely disabled by default.
+#
+# client_acl_blacklist:
+#   users:
+#     - root
+#     - '^(?!sudo_).*$'   #  all non sudo users
+#   modules:
+#     - cmd
 
 
 # The external auth system uses the Salt auth modules to authenticate and