message: proxy protocol stats docs
diff: @@ -25,3 +25,14 @@ If there is a protocol error or an unsupported address family
  * :ref:`v2 API reference <envoy_api_field_listener.Filter.name>`
  * This filter should be configured with the name *envoy.listener.proxy_protocol*.
  +
  +Statistics
  +----------
  +
  +This filter emits the following statistics:
  +
  +.. csv-table::
  + :header: Name, Type, Description
  + :widths: 1, 1, 2
  +
  + downstream_cx_proxy_proto_error, Counter, Total proxy protocol errors
  