tpa-rfc-73: document other options for the mirror pool

policy/tpa-rfc-73-tails-infra-merge-roadmap.md

@@ -565,8 +565,10 @@ This proposal is about:
   - https://tails.net/contribute/design/mirrors/
   - https://gitlab.torproject.org/tpo/tpa/tails/sysadmin/-/issues/18117 
   - [Tor's CDN][]
+  - [Other options][] discussed while dealing with router overload caused by Tails mirrors
 
  [Tor's CDN]:  https://gitlab.torproject.org/tpo/tpa/team/-/wikis/service/cdn
+ [Other options]: https://gitlab.torproject.org/tpo/tpa/tails/sysadmin/-/issues/18163#other-options
 
 ### Monitoring