docs: clarify that passing --depth to git-clone implies --single-branch
docs: clarify that passing --depth to git-clone implies --single-branch

It is confusing to document how --depth behaves as part of the
--single-branch docs. Better move that part to the --depth docs, saying
that it implies --single-branch by default.

Signed-off-by: Sebastian Schuberth <77397652b38ec60b50e56236b813774ce842bcdf@gmail.com>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git