Template repository for pyo3-polars

[universalmind303]

It'd be a nice addition to have a template repository that one can use when authoring new plugins.

[ohanf]

The userguide links to https://github.com/MarcoGorelli/cookiecutter-polars-plugins/tree/main which should do what you need, although you need cookiecutter instead of clicking a button in github. However the github templates do not include any actual templating, so setting things like the package name would need to be done manually vs cookiecutter doing it for you