Added postgres readme.
Added postgres readme.

yingjunwu/peloton,seojungmin/peloton,ShuxinLin/peloton,wangziqi2016/peloton,eric-haibin-lin/peloton-1,haojin2/peloton,AllisonWang/peloton,yingjunwu/peloton,haojin2/peloton,apavlo/peloton,PauloAmora/peloton,vittvolt/15721-peloton,AngLi-Leon/peloton,malin1993ml/peloton,AllisonWang/peloton,seojungmin/peloton,jessesleeping/iso_peloton,yingjunwu/peloton,ShuxinLin/peloton,apavlo/peloton,ShuxinLin/peloton,jessesleeping/iso_peloton,malin1993ml/peloton,haojin2/peloton,AllisonWang/peloton,jessesleeping/iso_peloton,malin1993ml/peloton,haojin2/peloton,eric-haibin-lin/peloton-1,PauloAmora/peloton,AngLi-Leon/peloton,PauloAmora/peloton,phisiart/peloton-p3,seojungmin/peloton,cmu-db/peloton,prashasthip/peloton,prashasthip/peloton,wangziqi2016/peloton,phisiart/peloton-p3,haojin2/peloton,wangziqi2016/peloton,wangziqi2016/peloton,cmu-db/peloton,prashasthip/peloton,eric-haibin-lin/peloton-1,AngLi-Leon/peloton,apavlo/peloton,phisiart/peloton-p3,jessesleeping/iso_peloton,apavlo/peloton,cmu-db/peloton,ShuxinLin/peloton,vittvolt/peloton,vittvolt/15721-peloton,vittvolt/peloton,cmu-db/peloton,apavlo/peloton,yingjunwu/peloton,PauloAmora/peloton,seojungmin/peloton,PauloAmora/peloton,vittvolt/15721-peloton,prashasthip/peloton,prashasthip/peloton,PauloAmora/peloton,AllisonWang/peloton,phisiart/peloton-p3,cmu-db/peloton,seojungmin/peloton,vittvolt/peloton,eric-haibin-lin/peloton-1,AngLi-Leon/peloton,phisiart/peloton-p3,vittvolt/peloton,malin1993ml/peloton,haojin2/peloton,ShuxinLin/peloton,vittvolt/15721-peloton,vittvolt/15721-peloton,wangziqi2016/peloton,yingjunwu/peloton,AllisonWang/peloton,phisiart/peloton-p3,eric-haibin-lin/peloton-1,cmu-db/peloton,yingjunwu/peloton,AngLi-Leon/peloton,AngLi-Leon/peloton,ShuxinLin/peloton,jessesleeping/iso_peloton,seojungmin/peloton,jessesleeping/iso_peloton,vittvolt/peloton,jessesleeping/iso_peloton,malin1993ml/peloton,prashasthip/peloton,vittvolt/peloton,apavlo/peloton,AllisonWang/peloton,eric-haibin-lin/peloton-1,vittvolt/15721-peloton,wangziqi2016/peloton,malin1993ml/peloton