message: Add `C-tracking-issue` tag to RFC merge procedure
diff: @@ -34,6 +34,7 @@ not forgotten
  Add the following labels to the issue:
  - `B-rfc-approved`
  +- `C-tracking-issue`
  - the approriate `T-XXX` label
  (If you don't have permissions to do so, leave a note cc'ing the appropriate
  