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/')"/>

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information