Add more metadata for Gitaly group

doc/administration/server_hooks.md

 ---
+stage: Create
+group: Gitaly
+info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers
 type: reference, howto
 disqus_identifier: 'https://docs.gitlab.com/ee/administration/custom_hooks.html'
 ---

doc/api/project_repository_storage_moves.md

+---
+stage: Create
+group: Gitaly
+info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#designated-technical-writers
+type: reference
+---
+
 # Project repository storage move API
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/31285) in GitLab 13.0.