There is also a nightly that is more current on the
OTA server (version 734, today) It includes a number of new features. The server in the link above is the first one listed in the OTA Servers found in the top menu once you have Koreader running. The OTA is just a wireless update function. I would rather just download it to my PC and copy over/merge the Koreader folder using the Start Menu's USB function.
Luck;
Ken