Recommend enabling integrity-checking in git

Recommend enabling integrity-checking in git

* admin/notes/git-workflow:  Recommend setting transfer.fsckObjects.

This is related to the autogen.sh changes made by Paul Eggert in
commit d766ca8f (2016-02-01) and commit cedd7cad (2016-02-01), and to
my edits today to http://www.emacswiki.org/emacs/GitForEmacsDevs and
to emacswiki.org/emacs/GitQuickStartForEmacsDevs.  See also the thread
"Recommend these .gitconfig settings for git integrity." at
https://lists.gnu.org/archive/html/emacs-devel/2016-01/threads.html#01802.