Changed user/admin to admin path

doc/api/broadcast_messages.md

doc/api/group_import_export.md

doc/api/issues.md

doc/api/lint.md

doc/api/notes.md

doc/api/project_import_export.md

doc/api/project_snippets.md

doc/api/projects.md

doc/api/repository_files.md

doc/api/settings.md

doc/api/snippets.md

doc/api/templates/dockerfiles.md

doc/ci/examples/index.md

doc/ci/migration/circleci.md

doc/ci/migration/jenkins.md

doc/ci/pipelines/settings.md

doc/ci/variables/predefined_variables.md