Merge branch 'docs/cell-router-prefix' into 'master'

Update Cells prefix routing spec

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/145639



Merged-by: Thong Kuah <tkuah@gitlab.com>
Approved-by: Thong Kuah <tkuah@gitlab.com>
Co-authored-by: Steve Xuereb <sxuereb@gitlab.com>

doc/architecture/blueprints/cells/routing-service.md

@@ -260,6 +260,8 @@ Each Cell will publish a precompiled list of routing rules that will be consumed
   routing rules to call `/api/v4/internal/cells/classify`.
 - The routing rules should use `prefix` as a way to speed up classification. During the compilation phase
   the routing service transforms all found prefixes into a decision tree to speed up any subsequent regex matches.
+- Some of the prefixes need to be Cell independent, example Personal Access Tokens prefix need to be organization bound and not Cell bound.
+  We want the ability to move an organization from 1 cell to another without changing the Personal Access Token or any other token.
 - The routing rules is ideally compiled into source code to avoid expensive parsing and evaluation of the rules
   dynamically as part of deployment.