http://www.codehaus.org/ is no longer supported. The reference to the new site for MVEL is not mentioned. The github site: https://github.com/mvel/mvel has a source and several trivial samples, but no links.
It was also removed from Wikipedia and moved to Wikisource: MVEL Language Guide
I posted the documentation in markdown format and posted the HTML version here: http://mvel.documentnode.com/
Please feel free to evolve from here: https://github.com/jiakuan/mvel-doc if something in the document needs to be improved.
I struggled with this content throughout the site. I found this from the wiki, not much information, but I hope that it will be useful for you before we can redirect another site. https://en.wikipedia.org/wiki/MVEL_Language_Guide
Check out this issue on the MVEL github repo: https://github.com/mvel/mvel/issues/101
Current documentation is here: http://mvel.documentnode.com/
You can find the full Mvel link in this archive: https://web.archive.org/web/20141017203926/http://mvel.codehaus.org/MVEL+2.0+Operators