Add Verify stage metadata to CI docs

doc/administration/environment_variables.md

doc/administration/external_pipeline_validation.md

doc/administration/feature_flags.md

doc/administration/job_artifacts.md

doc/administration/job_logs.md

doc/ci/README.md

doc/ci/caching/index.md

doc/ci/chatops/README.md

doc/ci/ci_cd_for_external_repos/bitbucket_integration.md

doc/ci/ci_cd_for_external_repos/github_integration.md

doc/ci/ci_cd_for_external_repos/index.md

doc/ci/directed_acyclic_graph/index.md

doc/ci/docker/README.md

doc/ci/docker/using_docker_build.md

doc/ci/docker/using_docker_images.md

doc/ci/docker/using_kaniko.md

doc/ci/enable_or_disable_ci.md

doc/ci/environments/incremental_rollouts.md

doc/ci/examples/README.md

doc/ci/examples/artifactory_and_gitlab/index.md