Bayescraft is just a synonym for Rationallity, with connotations of a) Bayes theorem, since that's what epistemic rationallity must be based on, and b) the notion that rationallity is a skill which must be developed personally and as a group (see also: Martial art of Rationallity (oh look, more capitals!))

The capitals are just for emphasis of concepts that the writer thinks are fundamentally important.