message: docs: clarify how to route on HTTP method
  Fixes
diff: @@ -6,6 +6,11 @@ Route
  A route is both a specification of how to match a request as well as in indication of what to do
  next (e.g., redirect, forward, rewrite, etc.).
  +.. attention::
  +
  + Envoy supports routing on HTTP method via :ref:`header matching
  + <config_http_conn_man_route_table_route_headers>`.
  +
  .. code-block:: json
  {
  @@ -317,6 +322,18 @@ regex
  Internally, Envoy always uses the HTTP/2 *:authority* header to represent the HTTP/1 *Host*
  header. Thus, if attempting to match on *Host*, match on *:authority* instead.
  +.. attention::
  +
  + To route on HTTP method, use the special HTTP/2 *:method* header. This works for both
  + HTTP/1 and HTTP/2 as Envoy normalizes headers. E.g.,
  +
  + .. code-block:: json
  +
  + {
  + "name": ":method",
  + "value": "POST"
  + }
  +
  .. _config_http_conn_man_route_table_route_weighted_clusters:
  Weighted Clusters
  