Broken links in documentation

[safelix]

Hi there,

This is just a small heads-up that the links of GGNLinearOperator and HessianLinearOperator point to the docs of scipy.sparse.linalg.LinearOperator instead of the respective classes in the basic example. This seems to be generally the case other classes which inherit from LinearOperator in other examples, but the basic example is the first I found.

Best, Felix