torbutton url changed, should update 'about' box
https://www.torproject.org/torbutton/ now redirects to https://www.torproject.org/docs/torbutton/
But src/chrome/content/about.xul still says
onclick="Components.classes['@mozilla.org/appshell/window-mediator;1'].getService(Components.interfaces.nsIWindowMediator).getMostRecentWindow('navigator:browser').open('https://www.torproject.org/torbutton/')"/>