setting ambari and hep repo per docs

http://public-repo-1.hortonworks.com/ambari/centos6/1.x/updates/1.5.1/ambari.repo
http://public-repo-1.hortonworks.com/HDP/centos6/2.x/GA/2.1-latest/hdp.repo

http://docs.hortonworks.com/HDPDocuments/Ambari-1.5.1.0/bk_using_Ambari_book/content/ambari-repositories.html
http://docs.hortonworks.com/HDPDocuments/Ambari-1.5.1.0/bk_using_Ambari_book/content/hdp-repositories.html
fixing README
referencing docker container by name