Fix Local Builds + Update: Hugo, MathJax, Mermaid

[thesuperzapper]

Because Hugo 0.125.0+ does not work (which will break people's ability to develop the website locally), I have put an explanation in the README of how users can downgrade hugo with brew.

This PR changes the behavior of the site to improve performance:

• Only load MathJax when mathjax: true is explicitly put in the header of the page:
  • NOTE: the only page using math is /docs/components/katib/hyperparameter/
• Only load Mermaid when a mermaid code block is present on the page
  • NOTE: the only page using mermaid is `/docs/components/notebooks/container-images/
• We now use the standard Hugo Syntax of \(INLINE_MATH\) rather than $INLINE_MATH$ which breaks other pages.

This PR also makes the following updates:

• Updates Hugo to 0.124.1 (WARNING: 0.125.0 does NOT work)
• Updates MathJax to 3.2.2
• Updates Mermaid to 10.9.0

[thesuperzapper]

@james-jwu @andreyvelich @jbottum this PR is small but important for 2 reasons:

1. Currently, if users follow the "local dev guide" hugo wont work (if they use the latest hugo).
2. It improves the performance of the website (only load heavy JS packages on the pages we actually use them).

I would appreciate your review.

[google-oss-prow[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: terrytangyuan, thesuperzapper

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