[Maven-site-plugin](http://maven.apache.org/plugins/maven-site-plugin/) supports [Markdown](http://en.wikipedia.org/wiki/Markdown) (*.md) markup language.
see http://stackoverflow.com/questions/14829190/how-to-use-markdown-for-maven-project-site

Markdown is also used by [gihub.com](https://help.github.com/articles/github-flavored-markdown), 
[SourceForge.net](http://sourceforge.net/p/subeditor/wiki/markdown_syntax/)
and [stackoverflow.com](http://stackoverflow.com/editing-help).

Visit the [official Markdown syntax reference page](http://daringfireball.net/projects/markdown/syntax).

Markdown support via [Markdown Editor plugin for Eclipse](http://www.winterwell.com/software/markdown-editor.php) developped by [Daniel Winterstein](http://winterstein.me.uk)    
	Download site: http://winterwell.com/software/updatesite/
	
Redmine uses different Textile markup language.
But there is [Markdown formatter plugin](http://www.redmine.org/projects/redmine/wiki/Plugin_List#Markdown-formatter-plugin) (not tried).