message: Update RFC template
diff: @@ -4,6 +4,8 @@ RFC: Your RFC
  <!-- RFCs start with the "RFC" status and are then either "Implemented" or "Rejected". -->
  > Status: RFC
  +>
  +> Applies to: client, server
  <!-- A great RFC will include a list of changes at the bottom so that the implementor can be sure they haven't missed anything -->
  For a summarized list of proposed changes, see the [Changes Checklist](#changes-checklist) section.
  