Correct text in mmil.html about number of axioms
Correct text in mmil.html about number of axioms

- There is a reference to 12 new (non-classical) axioms, but that
is out of date with the addition of ax-bnd. This number seems like
it could easily change again in the future.

- Don't link to ax-3.html, in preparation for the day when that
is removed from iset.mm.

metamath/set.mm,metamath/set.mm,metamath/set.mm