Resolve "CE documentation is not CommonMark compliant"

doc/user/group/subgroups/index.md

doc/user/markdown.md

doc/user/profile/account/two_factor_authentication.md

doc/user/project/bulk_editing.md

doc/user/project/clusters/eks_and_gitlab/index.md

doc/user/project/clusters/index.md

doc/user/project/container_registry.md

doc/user/project/cycle_analytics.md

doc/user/project/integrations/bamboo.md

doc/user/project/integrations/jira.md

doc/user/project/integrations/webhooks.md

doc/user/project/issue_board.md

doc/user/project/koding.md

doc/user/project/merge_requests/versions.md

doc/user/project/new_ci_build_permissions_model.md

doc/user/project/pages/index.md

doc/user/project/pipelines/job_artifacts.md

doc/user/project/pipelines/schedules.md

doc/user/project/protected_branches.md

doc/user/project/protected_tags.md