contributing: add new file with a pointer to the wiki
This also includes what I consider to be the minimum set of steps
someone should be able to perform even if they can't run the
testsuite. Hopefully this will help new contributors know to at least
run the two checkers that find most things that (in my experience)
require manual cleanup.
#require docutils gettext
$ $TESTDIR/check-gendoc el
checking for parse errors