Update readme.md
Update readme.md

Minor change in color highlight specification
sarathkrishna/2015-dataviscourse-homework,SMacNeil8/2015-dataviscourse-homework,shiow1991/2015-dataviscourse-homework,std2015/2015-dataviscourse-homework,dataviscourse/2015-dataviscourse-homework,jimibue/cs5360,SMacNeil8/2015-dataviscourse-homework,sarathkrishna/2015-dataviscourse-homework,shiow1991/2015-dataviscourse-homework,aywang/2015-dataviscourse-homework,jimibue/cs5360,aywang/2015-dataviscourse-homework,std2015/2015-dataviscourse-homework,dataviscourse/2015-dataviscourse-homework