Since 3ccd681c (Merge branch 'sb/submodule-rm-absorb', 2017-01-18)
git-rm tries to absorb any submodules git dir before deleting the
submodule. Correct the documentation to say so.
Signed-off-by: NStefan Beller <sbeller@google.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>