HDDS-1479. Update S3.md documentation
HDDS-1479. Update S3.md documentation

Closes #791

nandakumar131/hadoop,mapr/hadoop-common,steveloughran/hadoop,apache/hadoop,lukmajercak/hadoop,mapr/hadoop-common,mapr/hadoop-common,steveloughran/hadoop,apache/hadoop,lukmajercak/hadoop,mapr/hadoop-common,nandakumar131/hadoop,nandakumar131/hadoop,apurtell/hadoop,steveloughran/hadoop,wwjiang007/hadoop,JingchengDu/hadoop,wwjiang007/hadoop,JingchengDu/hadoop,JingchengDu/hadoop,nandakumar131/hadoop,plusplusjiajia/hadoop,apache/hadoop,JingchengDu/hadoop,lukmajercak/hadoop,apurtell/hadoop,plusplusjiajia/hadoop,wwjiang007/hadoop,plusplusjiajia/hadoop,apurtell/hadoop,wwjiang007/hadoop,lukmajercak/hadoop,apurtell/hadoop,apurtell/hadoop,plusplusjiajia/hadoop,mapr/hadoop-common,nandakumar131/hadoop,JingchengDu/hadoop,apurtell/hadoop,apurtell/hadoop,nandakumar131/hadoop,lukmajercak/hadoop,apache/hadoop,JingchengDu/hadoop,apache/hadoop,wwjiang007/hadoop,steveloughran/hadoop,mapr/hadoop-common,lukmajercak/hadoop,lukmajercak/hadoop,plusplusjiajia/hadoop,JingchengDu/hadoop,mapr/hadoop-common,steveloughran/hadoop,steveloughran/hadoop,plusplusjiajia/hadoop,nandakumar131/hadoop,apache/hadoop,steveloughran/hadoop,plusplusjiajia/hadoop,wwjiang007/hadoop,apache/hadoop,wwjiang007/hadoop