added 404 permalink accorrding to https://help.github.com/articles/creating-a-custom-404-page-for-your-github-pages-site/
added 404 permalink accorrding to https://help.github.com/articles/creating-a-custom-404-page-for-your-github-pages-site/

AAROC/hackfest-site,AAROC/hackfest-site,AAROC/hackfest-site,AAROC/hackfest-site