Add addtional fonts to CSS

[kesara]

Description

Breaking this away from #1281.
There are additional fonts used by some RFCs.
These should be added to the CSS:

• Noto Sans Math - https://static.ietf.org/fonts/noto-sans-math/import.css
• Noto Sans Symbols 2 -https://static.ietf.org/fonts/noto-sans-symbols-2/import.css

Code of Conduct

• I agree to follow the IETF's Code of Conduct