DOC: Add API Keys Info to Documentation

[zdomke]

Description

Update the documentation to include information on API Keys.

Includes info on:

• Managing keys using the scripts from ENH: Add API Key Management Scripts #48
• Using the keys with examples in python and javascript
• Some basic information on how the keys are stored/hashed

Motivation

Closes #35

Where Has This Been Documented?

Various places in the documentation, but mostly in the new api-keys.md page (view after running mkdocs serve)
http://127.0.0.1:8000/react-squirrel-backend/getting-started/api-keys/

Pre-merge checklist

• Code works interactively
• Code contains descriptive docstrings
• New/changed functions and methods are covered in the test suite where possible
• Test suite passes locally
• Test suite passes on GitHub Actions