git-cherry-pick.txt: clarify the use of revision range notation

git-cherry-pick.txt: clarify the use of revision range notation

When given a set of commits, cherry-pick will apply the changes for
all of them. Specifying a simple range will also work as expected.

This can lead the user to think that

    git cherry-pick A B..C

may apply A and then B..C, but that is not what happens.

Instead the revs are given to a single invocation of rev-list, which
will consider A and C as positive revs and B as a negative one.  The
commit A will not be used if it is an ancestor of B.

Add a note about this and add an example with this particular
syntax, which has shown up on the list a few times.

Signed-off-by: Carlos Martín Nieto <cmn@elego.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>