Fix backfill config comment

example-config.yaml

@@ -101,7 +101,8 @@ bridge:
         max_age: 604800
         # Enable backfilling history sync payloads from WhatsApp using batch sending?
         # This requires a server with MSC2716 support, which is currently an experimental feature in synapse.
-        # It can be enabled by setting experimental_features -> enable_msc2716 to true in homeserver.yaml.
+        # It can be enabled by setting experimental_features -> msc2716_enabled to true in homeserver.yaml.
+        # Note that as of Synapse 1.46, there are still some bugs with the implementation, especially if using event persistence workers.
         backfill: false
         # Use double puppets for backfilling?
         # In order to use this, the double puppets must be in the appservice's user ID namespace