Revamp examples repository

[iancze]

Objective: have an examples directory that is both useful and advertises what MPoL is capable of.

Plan:

• structure root README.md with w/ links to completed subdirectories. Relabel subdirectories with 01-, 02-, etc.
• create nested snakemake files capable of building all products, with the intention to build locally since significant computational resources are required and otherwise not available using GitHub actions free tier
• place appropriate outputs like images in version control and incorporate into .md files to showcase results. If dynamically-updated results are important, investigate using jinja2. But this may just be images, which is fine to do with a hard link.

I also considered resuscitating the Sphinx + Jupyter Notebook + nbsphinx build process, pushing static site to GitHub pages and then assemble + deploy with GitHub actions. However, we initially moved away from this because we felt that most imaging workflows are ill-suited to a Jupyter notebook style workflow, and benefit from being broken up into actual Python scripts. I think the directory approach is more useful, and actually mirrors the way the PyTorch examples are presented.

• Publish butterfly example / make more prominent