message: mysql_filter: add a warning about compatibility
  This adds a warning to the MySQL filter docs regarding compatibility
  issues with the filter.
diff: @@ -15,6 +15,11 @@ as operations performed on each table.
  development. Capabilities will be expanded over time and the
  configuration structures are likely to change.
  +.. warning::
  +
  + The mysql_proxy filter was tested with MySQL v5.5. The filter may not work
  + with other versions of MySQL due to differences in the protocol implementation.
  +
  .. _config_network_filters_mysql_proxy_config:
  Configuration
  