Improve English grammar and consistency. (#3614)
* Start improving English grammar and consistency.
* Apply review comments, push translation further.
* Additional review changes; expand translation.
* Undo team/organization change, further translation.
* Add site administration; review comments; merge.
* Update hardcoded branch protection string tests.
* Update hardcoded branch deletion string test.
* Update another hardcoded translation string test.
* Add my nickname to the list of translators.
* Implement @lafriks review comments.
* Remove (now) unused branch deletion warnings.
* Remove (now) unused branch deletion warnings.
bugreport0