Peter Debruge Chief Film Critic“Education.” That’s as good a title as any for the final episode of Steve McQueen’s “Small Axe” project — a series of five features, some little more than an hour, designed to educate and inform audiences about the experience of London’s West Indian immigrant population, about the expectations of assimilation raised by a white-majority country and the obstacles such a society puts in the way of that goal.To get the picture, audiences needn’t see every entry of