You can find more details on the TrueSkill page at Microsoft Research and the TrueSkill Wikipedia page. Also, Mike Moser’s excellent blogpost on TrueSkill explains all the underlying mathematics necessary to understand it.
TrueSkill is now textbook material, and, e.g., discussed in Kevin Murphy’s excellent textbook Machine Learning: A Probabilistic Perspective and in David Barber’s great book Bayesian Reasoning and Machine Learning
We later developed a generalisation of TrueSkill that makes it possible to track players’ skills through time, described in the NeurIPS paper TrueSkill Through Time. Most notably, it contains a plot of top chess players’ skill histories through time.