Added example gallery.

[qnguyen345]

Added example gallery containing the juypter notebooks into the sphinx documentation using nbsphinx. The missing juypter notebooks are the lidar ones, which will be added after lidar PR is merged into main. This addresses issues #47.

[kperrynrel]

This is looking totally awesome!!!! Can we change our installation process to what I put in the README and axe the section on "running a single system" in the Getting Started section?

[kperrynrel]

Found something else since I'm literally using this documentation to build the smoke plume maps for REGROW rn.... we should add the new weather models to the Models section:

[qnguyen345]

@kperrynrel Hey Kirsten, I put all your suggestions in the latest commit. I'm going to add sphinx documentation edits to this PR too because it's easier, but lmk if you want a separate PR for sphinx stuff. Take a quick look and let me know what you think and things that can be added. I still need to polish some stuff up like fixing the index page, but I think this is a good start to the documentation. We can talk more about it in our tag up tomorrow.

[qnguyen345]

Addresses Issue #13 in the latest sphinx push