📝DOC: Add overview and model concepts

[garland-culbreth]

Proposed changes

Add a new overview page to docs and incorporate examples into the site as the user guide.

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added the necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream modules