fix: missing MathJax resources

[scissorsneedfoodtoo]

Checklist:

• [x] I have read freeCodeCamp's contribution guidelines.
• [x] My pull request has a descriptive title (not a vague title like Update index.md)

Related to https://github.com/freeCodeCamp/cdn/pull/266

This updates News to use the new main MathJax script in the es5 directory, which also contains previously missing resources like a11y scripts and fonts.