doc/SubmittingPatches: clarify the casing convention for "area: change..."
Amend the section which describes how the first line of the subject
should look like to say that the ":" in "area: " shouldn't be treated
like a full stop for the purposes of letter casing.
Change the two subject examples to make this new paragraph clearer,
i.e. "unstar" is not a common word, and "git-cherry-pick.txt" is a
much longer string than "githooks.txt". Pick two recent commits from
git.git that fit better for the description.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>