update notification for release 0.42

Any feedback? Thanks!
@peterflynn @pthiess @JeffryBooher @ryanstewart @redmunds @dangoor @RaymondLim @larz0 
We also added a feature that shows which translations are available for each extension.  That actually seems valuable to more users than drag & drag, so I wonder if we should list that in addition / instead.