Add documentation on S3 scratch bucket

[scottyhq]

Addresses #68

[tsnow03]

I added 3 suggestions, but everything else looks great! Thanks Scott!

[jomey]

Not sure if this is a requirement here, but should the notebook be committed as rendered? More of a curious question.

[jomey]

Also along the lines of 'rendered version', would it be good to have this example not tailored to your GitHub username and use a generic one?
Mainly wondering if someone just wants to test this notebook and walks through the steps that this person might overwrite your personal bucket 😄

[scottyhq]

Not sure if this is a requirement here, but should the notebook be committed as rendered? More of a curious question.

CryoCloudWebsite/book/_config.yml

Lines 36 to 37 in 79d39c9

	execute:
	execute_notebooks: 'off'

Based on that setting the notebook must be rendered. Probably worth opening another issue to discuss simplifying github actions borrowed from the uw hackweeks.

[scottyhq]

would it be good to have this example not tailored to your GitHub username and use a generic one?

Good point! I'll use octocat

[scottyhq]

Thanks for the review @tsnow03 and @jomey I think this is ready to merge!