message: docs: update websocket.rst
  Link to RFC 8441 rather than the earlier working group draft.
  Fixes
diff: @@ -32,15 +32,15 @@ laid out below, but custom filter chains can only be configured on a per-HttpCon
  | F | F | F |
  +-----------------------+-------------------------+-------------------+
  -Note that the statistics for upgrades are all bundled together so websocket
  +Note that the statistics for upgrades are all bundled together so WebSocket
  :ref:`statistics <config_http_conn_man_stats>` are tracked by stats such as
  downstream_cx_upgrades_total and downstream_cx_upgrades_active
  Handling H2 hops
  ^^^^^^^^^^^^^^^^
  -Envoy currently has an alpha implementation of tunneling websockets over H2 streams for deployments
  -that prefer a uniform H2 mesh throughout, for example, for a deployment of the form:
  +Envoy supports tunneling WebSockets over H2 streams for deployments that prefer a uniform
  +H2 mesh throughout; this enables, for example, a deployment of the form:
  [Client] ---- HTTP/1.1 ---- [Front Envoy] ---- HTTP/2 ---- [Sidecar Envoy ---- H1 ---- App]
  @@ -48,7 +48,7 @@ In this case, if a client is for example using WebSocket, we want the Websocket
  upstream server functionally intact, which means it needs to traverse the HTTP/2 hop.
  This is accomplished via
  -`extended CONNECT <https://tools.ietf.org/html/draft-mcmanus-httpbis-h2-websockets>`_ support. The
  +`extended CONNECT <https://tools.ietf.org/html/rfc8441>`_ support. The
  WebSocket request will be transformed into an HTTP/2 CONNECT stream, with :protocol header
  indicating the original upgrade, traverse the HTTP/2 hop, and be downgraded back into an HTTP/1
  WebSocket Upgrade. This same Upgrade-CONNECT-Upgrade transformation will be performed on any
  