Footnotes
Footnotes are useful when you want to provide additional context about an item but that context would greatly distract from the flow of reading through the document (legal disclaimers, pricing, etc.).
We use https://littlefoot.js.org/, which helps us render fancy footnotes in context of what you are talking about (and also are much better for mobile).
To implement footnotes, use standard markdown footnote formatting. You can also see an example in the Load Balancing documentation