Merge branch 'tc-geo-dev-docs' into 'master'

Write some Geo dev docs

Closes #7685

See merge request gitlab-org/gitlab-ee!7452

doc/development/README.md

@@ -53,6 +53,7 @@ description: 'Learn how to contribute to GitLab.'
 - [Prometheus metrics](prometheus_metrics.md)
 - [Guidelines for reusing abstractions](reusing_abstractions.md)
 - [DeclarativePolicy framework](policies.md)
+- [Geo development](geo.md)
 
 ## Performance guides
 

ee/changelogs/unreleased/tc-geo-dev-docs.yml

+---
+title: Write some Geo development documentation
+merge_request: 7452
+author:
+type: other