Add uniaxial medium lithium niobate to material library

[weiliangjin2021]

Resolves #1413

The doc page for LiNiO3:

One question to @daquinteroflex: now I need to manually run python generate_doc.py to update material_library.rst, so that the doc page can include updated material library. Is that the expected behavior?

[tomflexcompute]

Thanks @weiliangjin2021 . This is a very nice addition. We can update this notebook to use the material library option later.

[daquinteroflex]

Ahh thanks for the catch Weiliang! What I will do is in the next docs PR, every time you run poetry run tidy3d develop build-docs, it automatically builds the material library just for the sake of convenience - or see if I can hook it into the sphinx build process.