Submodule functions should be represented with fully qualified names in the docs

[andykee]

When referring to classes and methods in submodules in the docs, it is preferable to provide a fully qualified name. For example,

detector.pixelate()

is preferable to

pixelate()

This is simple to achieve in the documentation:

.. currentmodule:: lentil

:func:`detector.pixelate`

The documentation should be globally updated to make this change.