message: docs: Fix typo
  Noted while skimming through
diff: @@ -232,7 +232,7 @@ x-envoy-attempt-count
  ^^^^^^^^^^^^^^^^^^^^^
  Sent to the upstream to indicate which attempt the current request is in a series of retries. The value
  -will be "1" on the initial request, incremeting by one for each retry. Only set if the
  +will be "1" on the initial request, incrementing by one for each retry. Only set if the
  :ref:`include_attempt_count_header <envoy_api_field_route.VirtualHost.include_request_attempt_count>`
  flag is set to true.
  