With the new Help Center (and even before, if I am not mistaken) it appears possible to insert (with community manager assistance) new sections that are site-specific (and moderator editable). I propose that we request the addition of a "Notation" (or similarly named) section. Physics.SE and chemistry.SE both have such sections, and while basic information about MathJax/$\LaTeX$ and pointers appear in our on-topic page, in my opinion it makes more sense to have a dedicated section about this.
Below I have essentially just copied the content of the physics.SE notation page, with only minor changes. It is Community Wiki, so please improve it!