Describe file structure created by `nbdev_new`

[seeM]

Inspired by VSCode's extensions docs:

Here's the structure created by nbdev_new as of writing:

$ tree -a -I .git -I .quarto
.
├── .github
│   └── workflows
│       ├── deploy.yaml
│       └── test.yaml
├── .gitignore
├── 00_core.ipynb
├── LICENSE
├── MANIFEST.in
├── README.md
├── _docs
│   ├── robots.txt
│   └── sitemap.xml
├── _quarto.yml
├── index.ipynb
├── settings.ini
├── setup.py
├── styles.css
└── {lib_path}
    ├── __init__.py
    ├── _modidx.py
    └── core.py

[tylere]

This could be even more useful if it was expanded to other commands beyond nbdev_new, and it would useful to know what files each nbdev_* command expects to be in place when it runs, and what files are created/modified when the command runs.

Examples of specific questions this could answer:

• What command(s) creates/updates the _proc directory (so that I can then experiment with using quarto directly)?
• What command(s) updates the _docs directory?
• What are the pre-reqs for a successful run of nbdev_release_git? (i.e. create a .pypirc file)