Use runic on docs and fix up some other formatting

[abhro]

Checklist

• Appropriate tests were added
• Any code changes were done in a way that does not break public API
• All documentation related to code changes were updated
• The new code follows the contributor guidelines, in particular the SciML Style Guide and COLPRAC.
• Any new documentation only uses public API

Additional context

Uses runic on docs (using --docstrings and --extensions=jl,md on the runic CLI app) and reformats some lines for easier reading.