changelog: mention the conditional user creation feature (now that it's fixed)
changelog: mention the conditional user creation feature (now that it's fixed)

aptivate/etherpad-lite,aptivate/etherpad-lite,joequant/etherpad-lite,joequant/etherpad-lite,storytouch/etherpad-lite,ether/etherpad-lite,storytouch/etherpad-lite,joequant/etherpad-lite,storytouch/etherpad-lite,ether/etherpad-lite,aptivate/etherpad-lite,ether/etherpad-lite,joequant/etherpad-lite,aptivate/etherpad-lite