hacking: some more fixlets

hacking: some more fixlets

* HACKING (Release Procedure): Place the list of pre-release
bootstrap-and-test commands on a line of its own, so it's easy to
select and then paste it into a terminal window.
Fix the explanation of "make git-release", as, since the previous
change, "make git-release" would simply run "make dist" rather
than "make distcheck".

Suggestion from Jim Meyering.