Update logistic-regression.md

[charlottejmc]

I've changed the formatting in the lesson to use $$ around mathematical formulas.

Closes #3283

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[charlottejmc]

This is not rendering in the Netlify preview how I anticipated. I'll come back to this next week!

[miy-h]

It looks that the symbol | in math block is parsed as Markdown's table delimiter by kramdown, a Markdown parser used in jekyll. Maybe it is a bug of kramdown, but fixing it is difficult because kramdown is not actively maintained.

Instead, I suggest replacing X|Y with X \vert Y in math block. \vert represents | exactly in TeX and can be rendered by MathJax.

[charlottejmc]

Hello @miy-h,

Thank you so much for contributing to this issue. Your solution worked perfectly! We're just fixing a separate build issue before merging this PR, but you can see from the Netlify preview that your suggestion was successful :)

ありがとうございました ✨

[anisa-hawes]

Many thanks for your contribution @miy-h!

+ Thank you @charlottejmc for coordinating.