[#452] wire Discourse topic t/338 into README

https://projects.knownelement.com/issues/452#note-4538

README.md

@@ -15,7 +15,7 @@ skilled, well-resourced attackers. FedRAMP-style audit readiness.
 | Redmine project | [compliance-security](https://projects.knownelement.com/projects/compliance-security) — umbrella [#311](https://projects.knownelement.com/issues/311) |
 | CMMC program | [#452](https://projects.knownelement.com/issues/452) gap analysis to CMMC L3 / facility clearance |
 | Related | [#382](https://projects.knownelement.com/issues/382) STIG/SCAP, [#389](https://projects.knownelement.com/issues/389) OpenVAS/GVM on kali-tsys, [#381](https://projects.knownelement.com/issues/381) CIS hardening, [#379](https://projects.knownelement.com/issues/379) compliance test lab (sectestbed), [#804](https://projects.knownelement.com/issues/804) second approver |
-| Discourse | compliance topic (link lands at repo birth) |
+| Discourse | https://community.turnsys.com/t/338 |
 
 ## Layout (seeded 2026-09-05, growth expected)