[yardasol]

What is the change? Why is it being made?

This PR spruces up the blueprint user guide.

SCR Information

Change Type: docs

One-Sentence Rationale: ARMI docs should be clear and easy to understand.

One-line Impact on Requirements: NA

---

Checklist

• This PR has only one purpose or idea.
• Tests have been added/updated to verify any new/changed code.
• The documentation is still up-to-date in the doc folder.
• The code style follows good practices.
• The dependencies are still up-to-date in pyproject.toml.