Fix up sample config

docs/sample_config.yaml

@@ -954,8 +954,10 @@ password_config:
 
 # User Directory configuration
 #
-# 'enabled' defines whether users can search the user directory,
-#  defaults to True.
+# 'enabled' defines whether users can search the user directory. If
+# false then empty responses are returned to all queries. Defaults to
+# true.
+#
 # 'search_all_users' defines whether to search all users visible to your HS
 # when searching the user directory, rather than limiting to users visible
 # in public rooms.  Defaults to false.  If you set it True, you'll have to run

synapse/config/user_directory.py

@@ -37,8 +37,10 @@ class UserDirectoryConfig(Config):
         return """
         # User Directory configuration
         #
-        # 'enabled' defines whether users can search the user directory,
-        # Defaults to true.
+        # 'enabled' defines whether users can search the user directory. If
+        # false then empty responses are returned to all queries. Defaults to
+        # true.
+        #
         # 'search_all_users' defines whether to search all users visible to your HS
         # when searching the user directory, rather than limiting to users visible
         # in public rooms.  Defaults to false.  If you set it True, you'll have to run