Add angle brackets around URLs in docstrings

[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

Helps markdown parsers pick them up as URLs, and also, since they contain underscores, removes the cue to start italicizing text