The Markdown markup language is perfect for writing system administrator documentation: it is lightweight, versatile, and easy to learn, so you spend your time writing instead of fighting with formatting.
The life of a Linux system administrator is complex and varied, and you know that documenting your work is a big time-saver. A documentation web server shared by you and your colleagues is a wonderful productivity tool. Most of us know simple HTML, and can whack up a web page as easily as writing plain text. But using Markdown is better.