added FAQ about multiple iterators
added FAQ about multiple iterators

carolinux/pysam,kyleabeauchamp/pysam,carolinux/pysam,nlhepler/pysam,bioinformed/pysam,brendanofallon/pysam,bioinformed/pysam,nlhepler/pysam,kyleabeauchamp/pysam,kyleabeauchamp/pysam,dannon/pysam,mattions/pysam,daler/pysam,brendanofallon/pysam,TyberiusPrime/pysam,nlhepler/pysam,brendanofallon/pysam,daler/pysam,pysam-developers/pysam,TyberiusPrime/pysam,dannon/pysam,brendanofallon/pysam,mattions/pysam,nlhepler/pysam,daler/pysam,carolinux/pysam,dannon/pysam,pysam-developers/pysam,pysam-developers/pysam,mattions/pysam,kyleabeauchamp/pysam,dannon/pysam,bioinformed/pysam,pysam-developers/pysam,daler/pysam,mattions/pysam,carolinux/pysam,TyberiusPrime/pysam,mattions/pysam,bioinformed/pysam,TyberiusPrime/pysam,carolinux/pysam,daler/pysam,bioinformed/pysam,dannon/pysam,nlhepler/pysam,kyleabeauchamp/pysam,TyberiusPrime/pysam,brendanofallon/pysam