Currently, the WeierstrassIsomorphism class doesn't actually specify how the isomorphism given by a tuple (u,r,s,t) is defined.
While this is fairly standard, it can't hurt to make it more explicit in the documentation, hence this very simple patch.

(The related baseWI class does show the coordinate transform, but it's written in the form corresponding more easily to the inverse isomorphism, and the change in curve models is not shown.)

Component: elliptic curves

Author: Lorenz Panny

Issue created by migration from https://trac.sagemath.org/ticket/34439