Mark pages as owned by Release Mgmt team

Make it easier to see who owns the content of this page.

doc/api/deployments.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
+---
+
 # Deployments API
 ## List project deployments

doc/api/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
+---
+
 # Environments API
 ## List environments

doc/api/freeze_periods.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
+---
+
 # Freeze Periods API
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/29382) in GitLab 13.0.

doc/api/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
+---
+
 # Protected environments API **(PREMIUM)**
 > [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/30595) in [GitLab Premium](https://about.gitlab.com/pricing/) 12.8.