Merge branch 'docs-structure-metadata' into 'master'

Docs: Update metadata with Style Guide group link

See merge request gitlab-org/gitlab!42235

doc/development/documentation/structure.md

 ---
+stage: none
+group: Style Guide
+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
 description: What to include in GitLab documentation pages.
 ---