[SteveLAnderson]

If by technical documentation you mean a readme page, or a few internal pages, then either are fine, as are AsciiDoc, org, etc. There's no huge advantage or disadvantage to any of them; use the one that is easiest for you to write in without having to look up cheatsheets.

A lightweight markup language is designed to for the user to quickly write something, and most of them have been designed with the goal of having programmers document their work without having to learn a complicated tool. If you need to write extensions for a lightweight markup language, you're using it wrong.

For anything more than that, I'd use something designed for technical documentation (DITA and DocBook come to mind).

Lightweight markup languages seem easy, and, in the beginning they are, but over time, as revisions pile up and more people work on it and you find you have more requirements than you thought you had, they become a huge hassle. You spend more time fiddling than writing. There's a reason professional writers tend to use richer tools - they make their jobs easier and they make the result better.