added description to README.md
added description to README.md

murdinc/cli,ykanda/cli,ykanda/cli,codegangsta/cli,cmars/tools,minio/cli,cmars/tools,kohkimakimoto/cli,minio/cli,pjvds/cli,phinnaeus/cli,cmars/tools,cmars/tools,pjvds/cli,urfave/cli,phinnaeus/cli,ykanda/cli,phinnaeus/cli,codegangsta/cli,murdinc/cli,minio/cli,murdinc/cli,urfave/cli,pjvds/cli