[sf-perl] s/Mongers//g

[Joseph Brenner]

I just thought I'd mention I'd gradually trying to downplay the "Perl
Mongers" joke (there are other things I'd rather explain to people):
my goal is to change this group into "San Francisco Perl".  I was just
messing around with the meetup settings and it turns out it's much
easier to do the switch than I thought: the old links re-direct
correctly, and so on.