message: doc: Update recommended edge settings to reject requests with underscores
diff: @@ -23,6 +23,7 @@ HTTP proxies should additionally configure:
  * :ref:`HTTP/2 maximum concurrent streams limit <envoy_api_field_core.Http2ProtocolOptions.max_concurrent_streams>` to 100,
  * :ref:`HTTP/2 initial stream window size limit <envoy_api_field_core.Http2ProtocolOptions.initial_stream_window_size>` to 64 KiB,
  * :ref:`HTTP/2 initial connection window size limit <envoy_api_field_core.Http2ProtocolOptions.initial_connection_window_size>` to 1 MiB.
  +* :ref:`headers_with_underscores_action setting <envoy_api_field_core.HttpProtocolOptions.headers_with_underscores_action>` to REJECT_REQUEST, to protect upstream services that treat '_' and '-' as interchangeable.
  The following is a YAML example of the above recommendation.
  @@ -83,6 +84,7 @@ The following is a YAML example of the above recommendation.
  use_remote_address: true
  common_http_protocol_options:
  idle_timeout: 3600s # 1 hour
  + headers_with_underscores_action: REJECT_REQUEST
  http2_protocol_options:
  max_concurrent_streams: 100
  initial_stream_window_size: 65536 # 64 KiB
  