Yeah, I'm less than thrilled with respect to what they do with firmware releases. I infer Obihai wants $10 USD annually for people to obtain firmware from Obitalk.com web accounts instead. But you can't find release notes there either.
And dialing ***6 won't always update you to the latest firmware either anymore, even if you've paid $10 USD for extended support.
OBi200/202 Freephonline PDF guide (version 1.51x) can be found here.