Docs: Added metadata

For Release Management and Progressive Delivery
Related to: https://gitlab.com/gitlab-org/gitlab/-/issues/216290

doc/ci/cloud_deployment/index.md

 ---
+stage: Release
+group: Progressive Delivery
+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: howto
 ---
 

doc/ci/environments/environments_dashboard.md

 ---
+stage: Release
+group: Release Management
+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
 ---
 

doc/ci/environments/index.md

 ---
+stage: Release
+group: Release Management
+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
 disqus_identifier: 'https://docs.gitlab.com/ee/ci/environments.html'
 ---

doc/ci/environments/protected_environments.md

 ---
+stage: Release
+group: Release Management
+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: concepts, howto
 ---
 

doc/ci/review_apps/index.md

 ---
+stage: Release
+group: Progressive Delivery
+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
 ---
 

doc/integration/vault.md

 ---
+stage: Release
+group: Release Management
+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
 ---
 

doc/user/project/operations/feature_flags.md

+---
+stage: Release
+group: Progressive Delivery
+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
+---
+
 # Feature Flags **(PREMIUM)**
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/7433) in GitLab 11.4.

doc/user/project/releases/index.md

 ---
 type: reference, howto
+stage: Release
+group: Release Management
+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
 ---
 
 # Releases