Moved labels onto its own page

doc/development/code_review.md

doc/development/contributing/design.md

doc/development/contributing/index.md

doc/development/contributing/issue_workflow.md

doc/development/contributing/merge_request_workflow.md

doc/development/documentation/workflow.md

doc/development/labels/index.md

doc/policy/maintenance.md

doc/user/application_security/api_fuzzing/index.md

.../application_security/api_security/api_discovery/index.md

doc/user/application_security/dast_api/index.md