Fix more vale warnings

doc/.vale/gitlab/Uppercase.yml

doc/development/internal_api/index.md

doc/development/workhorse/configuration.md

doc/development/workhorse/gitlab_features.md

doc/user/admin_area/settings/index.md

...ser/admin_area/settings/visibility_and_access_controls.md

doc/user/asciidoc.md

doc/user/project/highlighting.md

doc/user/project/repository/branches/default.md

doc/user/project/repository/branches/index.md

doc/user/project/repository/csv.md