add example notebooks

[alexpiet]

• Right now we have example code snippets in the readme. It would be beneficial to have examples in notebooks.
• Ideally when a new feature is added, we also add a new example notebook.

@bwtan-allen this might be a good way to get started contributing

[rachelstephlee]

I have example notebooks here: https://codeocean.allenneuraldynamics.org/capsule/1126083/tree?cw=true

@rachelstephlee will link this capsule/repo to the readme.

[rachelstephlee]

https://codeocean.allenneuraldynamics.org/capsule/6488619/tree

use this one instead