www: update the "Follow what's going on" section too

Includes some style tweaks and removes the tautological observation that "Clang
is still under heavy development" -- it hopefully always will be.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@199401 91177308-0d34-0410-b5e6-96231b3b80d8