Link to wiki page:
https://github.com/koreader/koreader...eader-Gestures
Maybe it's something for multitouch (i.e., Kindle)? I'm not really sure what that's referring to; hopefully I'll remember to take a look at the code later.
Edit: my assumption looks to be correct:
https://github.com/koreader/koreader/issues/640
Ideally someone with a device that supports it so they know how it works should edit the wiki to clarify.