Add pdoc autogenerated docs

[wtong98]

Some quick-n-dirty documentation addressing #15

These doc files were generated automatically from existing docstrings using pdoc3. It does a pretty good job of parsing most things, and huge shoutout to the maintainers for keeping crisp, clean docstrings, but it cannot catch everything. In particular, I've omitted everything under note_seq/alignment. These files are not generated automatically, but if you'd like, we can discuss additional infrastructure to do so.

This is certainly not a long-term solution, but a quick fix so users don't have to go digging in source to read the docs. For convenience, I've also tossed the files here, where they can be browsed: https://wlt.coffee/cream/docs/note_seq/

Ideally, we would have a proper readthedocs site, but that would be a much longer, time-consuming project. In the meanwhile, I hope people find this useful!

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[wtong98]

@googlebot I signed it!