Add docs around installing packages via pip

[kcpevey]

Reference Issues or PRs

Resolves #411

What does this implement/fix?

This adds docs for installing private packages on Nebari. As I was writing, I realized that I also answer a lot of questions around installing pip packages in general so I've added those as well.

Put a x in the boxes that apply

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds a feature)
• Breaking change (fix or feature that would cause existing features not to work as expected)
• Documentation Update
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build related changes
• Other (please describe):

Testing

• Did you test the pull request locally?
• Did you add new tests?

Documentation

Access-centered content checklist

Text styling

• The content is written with plain language (where relevant).
• If there are headers, they use the proper header tags (with only one level-one header: H1 or # in markdown).
• All links describe where they link to (for example, check the Nebari website).
• This content adheres to the Nebari style guides.

Non-text content

• All content is represented as text (for example, images need alt text, and videos need captions or descriptive transcripts).
• If there are emojis, there are not more than three in a row.
• Don't use flashing GIFs or videos.
• If the content were to be read as plain text, it still makes sense, and no information is missing.

Any other comments?

[netlify]

✅ Deploy Preview for nebari-docs ready!

Name	Link
🔨 Latest commit	90f8546
🔍 Latest deploy log	https://app.netlify.com/sites/nebari-docs/deploys/66d881ee63f74b000862b79a
😎 Deploy Preview	https://deploy-preview-484--nebari-docs.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[Adam-D-Lewis]

@kcpevey It's awesome to see this guide for users!

[kcpevey]

@Adam-D-Lewis can you give a formal review?

[Adam-D-Lewis]

A few minor comments, but approved. Thanks for the great write up!

[viniciusdc]

@kcpevey Left some small suggestions

[kcpevey]

All requested changes have been applied!