tell users what's going on when a new munge set is out

Since people don't learn and start freaking out as soon as IITC breaks, maybe it's a good idea to tell them what's happening and why. Detecting that a new (or at least undetectable) munge set is out is pretty safe ("missing version"), so this should not cause false information.

I can live with this being denied, however. It's really just a suggestion. I would be happy to adjust the text if needed :-)