message: doc: fix SNI FAQ link
diff: @@ -70,9 +70,9 @@ The following is a YAML example of the above requirement.
  How do I configure SNI for clusters?
  ====================================
  -For clusters, a fixed SNI can be set in `UpstreamTlsContext <envoy_api_field_auth.UpstreamTlsContext.sni>`_.
  +For clusters, a fixed SNI can be set in :ref:`UpstreamTlsContext <envoy_api_field_auth.UpstreamTlsContext.sni>`.
  To derive SNI from HTTP `host` or `:authority` header, turn on
  -`auto_sni <envoy_api_field_core.UpstreamHttpProtocolOptions.auto_sni>`_ to override the fixed SNI in
  +:ref:`auto_sni <envoy_api_field_core.UpstreamHttpProtocolOptions.auto_sni>` to override the fixed SNI in
  `UpstreamTlsContext`. If upstream will present certificates with the hostname in SAN, turn on
  -`auto_san_validation <envoy_api_field_core.UpstreamHttpProtocolOptions.auto_san_validation>`_ too.
  +:ref:`auto_san_validation <envoy_api_field_core.UpstreamHttpProtocolOptions.auto_san_validation>` too.
  It still needs a trust CA in validation context in `UpstreamTlsContext` for trust anchor.
  