Add missing blank line in config (#5249)

changelog.d/5249.feature

@@ -0,0 +1 @@
+Ability to configure default room version.

docs/sample_config.yaml

@@ -90,6 +90,7 @@ pid_file: DATADIR/homeserver.pid
 #
 # For example, for room version 1, default_room_version should be set
 # to "1".
+#
 #default_room_version: "1"
 
 # The GC threshold parameters to pass to `gc.set_threshold`, if defined

synapse/config/server.py

@@ -414,6 +414,7 @@ class ServerConfig(Config):
         #
         # For example, for room version 1, default_room_version should be set
         # to "1".
+        #
         #default_room_version: "%(default_room_version)s"
 
         # The GC threshold parameters to pass to `gc.set_threshold`, if defined