Merge branch 'lo/repo-leftover-bits'

Merge branch 'lo/repo-leftover-bits'

Clean-up the code around "git repo info" command.

* lo/repo-leftover-bits:
  Documentation/git-repo: capitalize format descriptions
  Documentation/git-repo: replace 'NUL' with '_NUL_'
  t1901: adjust nul format output instead of expected value
  t1900: rename t1900-repo to t1900-repo-info
  repo: rename struct field to repo_info_field
  repo: replace get_value_fn_for_key by get_repo_info_field
  repo: rename repo_info_fields to repo_info_field
  CodingGuidelines: instruct to name arrays in singular