The link in the /sci/'s sticky is dead because the guy who hosted the sites.google.com wiki has been banned by Google for violating ToS. The link used to lead to a (dead) wiki which was never worked on or finished.

I suggest that it's replaced with a new sticky that has:
>explanation how to use MathJAX
>reminder to go to /adv/ and /wsr/ for career advice and homework requests respectively
>useful resources (such as nLab (a well known math wiki), arXiv (a well known prepublication website), MathJaX documentation etc.) like there are on other boards such as /fit/ and /int/

Here, I made a example sticky combining the /g/ and /int/ stickies that would work as a drop-down replacement for the sticky on /sci/:

>This board is for the discussion of science and math
>
>If you want advice regarding college/university or your career path, go to >>>/adv/ - Advice.
>If you want help with your homework, go to >>>/wsr/ - Worksafe Requests.
>
>To use MathJaX, put your TeX code between [math] ... [/math] tags (inline equations) or [eqn] ... [/eqn] tags (block equation).
>Note: You may preview the output by clicking the TeX button at the top left corner in the quick reply window.
>
>Useful resources:
>https://docs.mathjax.org/
>https://ncatlab.org/
>https://arxiv.org/
>https://mathoverflow.net/
>https://warosu.org/sci/