add application check commands
make bullet punctuation consistent
Make file edit error message less specific

The truth is that at the point where there error message is written we
can only guess what went wrong.
List API file edit failure conditions in docs
Add comments.
Merge branch 'doc/api_file_edit' into 'master'

Make file edit error message less specific

See merge request !1007
Merge pull request #7433 from bbodenmiller/patch-1

add application check commands to 5.0 to 5.1 upgrade guide
Fix spelling errors in doc, closes #7437

Further changes
Merge pull request #7434 from Razer6/fix_spelling_error

Fix spelling errors in documentation
Merge pull request #7442 from bbodenmiller/patch-9

make bullet punctuation on protected branches page consistent
Merge branch 'master' of github.com:gitlabhq/gitlabhq