--branch::
Branch of repository to add as submodule.
The name of the branch is recorded as `submodule.<name>.branch` in
- `.gitmodules` for `update --remote`.
+ `.gitmodules` for `update --remote`. A special value of `.` is used to
+ indicate that the name of the branch in the submodule should be the
+ same name as the current branch in the current repository.
-f::
--force::