Add more metadata to dev docs

doc/development/cicd/index.md

+---
+stage: Verify
+group: Continuous Integration
+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: index, concepts, howto
+---
+
 # CI/CD development documentation
 
 Development guides that are specific to CI/CD are listed here.

doc/development/cicd/templates.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: index, concepts, howto
+---
+
 # Development guide for GitLab CI/CD templates
 
 This document explains how to develop [GitLab CI/CD templates](../../ci/examples/README.md).

doc/development/doc_styleguide.md

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 redirect_to: 'documentation/styleguide.md'
 ---
+
+This document was moved to [another location](documentation/styleguide.md).

doc/development/feature_flags.md

+---
+redirect_to: 'feature_flags/index.md'
+---
+
 This document was moved to [another location](feature_flags/index.md).