[SG2] Added Errata

My apologies to folks getting this twice.

I just found out from Jon that the +1/+0/NTR Confidence Test modifier
for
Abandoned Casualties in Stargrunt II should be +1/+0/+0. I have updated
this, plus a clarification on how the Confidence Tests work, on my web site.
The
site is: http://sg2.hyperbear.com. Click on the Errata link.