Missing documentation and examples: Simplification of diagrams using genetic algorithms

[jvdwetering]

Over the years, several additional features have been merged into PyZX that have never had documentation written for them. One of these features is simplification of diagrams using genetic algorithms, as implemented in the pyzx.local_search subfolder by Ryan Krueger.

To close this issue:

• Add docstrings to the functions that are in pyzx.local_search explaining the parameters.
• Create a Jupyter notebook in the demos folder that demonstrates some toy examples of routing.
• Add some of the relevant functions to the demos/AllFeatures notebook.
• Add a section or paragraph to the docs explaining this functionality.