What's a good markup language to write user manuals in?

The answers given so far are good for API or shorter usage guides, but if you are composing a serious body of text, you need a serious composing tool. The question you posted gives a pretty good run-down of the strengths of several heavy-hitters in this category, so I won't rehash them.

Steve Streeting, the (former) project lead for OGRE, recently wrote an article about his new documentation toolchain which starts out with ASCIIDoc and ends up as PDF: Building a new technical documentation tool chain. It includes full setup instructions for ASCIIDoc, DocBook and FOP on Windows.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.