Fix metadata capitalization

Fix group/stage name in metadata.

doc/architecture/blueprints/gitlab_to_kubernetes_communication/index.md

 ---
-stage: configure
-group: configure
+stage: Configure
+group: Configure
 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
 comments: false
 description: 'GitLab to Kubernetes communication'