A prerequisites panel for each page

[Strokkur424]

I think the docs could benefit from certain pages having some way to check the page's prerequisites. This way, if a page is linked to a new user, they do not get confused about some used API, which is explained on a different page. This would also remove the need to give a brief explanation on some slightly niche, but still documented API if it is used on another page.

Currently not sure how that would look. It could be on the side bar, just like the 'written-for' label?

[Leguan16]

I don't know about naming them prerequisites. Maybe "See also" or something.