The Real-Time Communications (RTC) Quick Start Guide started off as a web site but has recently undergone bookification.
As of today, I'm calling this a beta release, although RTC is a moving target and even when a 1.0 release is confirmed, the book will continue to evolve.
An important aspect of this work is that the book needs to be freely and conveniently available to maximize participation in Free RTC. (This leads to the question of which free license should I choose?)