Tidy docs

[zorian15]

Description

A lot of TLC for the docs. Mainly addressing lingering TODOs. A summary of the changes include:

• Schematic images for torchdms models
• A notebook with math write ups for torchdms models
• Some tweaks to the CLI tutorials

No direct issue for these things, but should be able to close a lot of the old issues -- Closes #160 #161 and #131

Tests

The build okay locally 😅

Checklist:

• [x] The code uses informative and accurate variable and function names
• [ ] The functionality is factored out into functions and methods with logical interfaces
• [x] Comments are up to date, document intent, and there are no commented-out code blocks
• [x] Commenting and/or documentation is sufficient for others to be able to understand intent and implementation
• [ ] TODOs have been eliminated from the code
• [x] The corresponding issue number (e.g. #278) has been searched for in the code to find relevant notes
• [ ] Documentation has been redeployed