modify back some explanations for IO param, suggest manually write io.md
modify back some explanations for IO param, suggest manually write io.md

Ldpe2G/mxnet,Northrend/mxnet,szha/mxnet,eric-haibin-lin/mxnet,larroy/mxnet,nicklhy/mxnet,sergeykolychev/mxnet,Northrend/mxnet,DR08/mxnet,ZihengJiang/mxnet,yajiedesign/mxnet,vikingMei/mxnet,DR08/mxnet,likelyzhao/mxnet,precedenceguo/mxnet,crazy-cat/incubator-mxnet,Mega-DatA-Lab/mxnet,jamesliu/mxnet,luoyetx/mxnet,szha/mxnet,tornadomeet/mxnet,kevinthesun/mxnet,zhreshold/mxnet,hesseltuinhof/mxnet,dmlc/mxnet,luoyetx/mxnet,TuSimple/mxnet,szha/mxnet,yuruofeifei/mxnet,mbaijal/incubator-mxnet,jermainewang/mxnet,stefanhenneking/mxnet,ykim362/mxnet,gautamkmr/incubator-mxnet,rahul003/mxnet,crazy-cat/incubator-mxnet,LinkHS/incubator-mxnet,nicklhy/mxnet,jamesliu/mxnet,kevinthesun/mxnet,kkk669/mxnet,gautamkmr/incubator-mxnet,kevinthesun/mxnet,precedenceguo/mxnet,ShownX/incubator-mxnet,ZihengJiang/mxnet,zhreshold/mxnet,jennyzhang0215/incubator-mxnet,kkk669/mxnet,tlby/mxnet,ptrendx/mxnet,tlby/mxnet,navrasio/mxnet,sergeykolychev/mxnet,crazy-cat/incubator-mxnet,tornadomeet/mxnet,solin319/incubator-mxnet,ZihengJiang/mxnet,leezu/mxnet,smolix/incubator-mxnet,stefanhenneking/mxnet,dmlc/mxnet,yuruofeifei/mxnet,apaleyes/mxnet,precedenceguo/mxnet,reminisce/mxnet,weleen/mxnet,piiswrong/mxnet,LinkHS/incubator-mxnet,hpi-xnor/BMXNet,danithaca/mxnet,reminisce/mxnet,formath/mxnet,eric-haibin-lin/mxnet,jamesliu/mxnet,LinkHS/incubator-mxnet,jiajiechen/mxnet,DR08/mxnet,hpi-xnor/BMXNet,formath/mxnet,arank/mxnet,solin319/incubator-mxnet,CodingCat/mxnet,ZihengJiang/mxnet,crazy-cat/incubator-mxnet,Prasad9/incubator-mxnet,rishita/mxnet,likelyzhao/mxnet,vikingMei/mxnet,kevinthesun/mxnet,madjam/mxnet,arikpoz/mxnet,solin319/incubator-mxnet,xcgoner/dist-mxnet,antoan2/incubator-mxnet,yajiedesign/mxnet,mbaijal/incubator-mxnet,ShownX/incubator-mxnet,formath/mxnet,xcgoner/dist-mxnet,eric-haibin-lin/mxnet,rishita/mxnet,CodingCat/mxnet,tornadomeet/mxnet,madjam/mxnet,arikpoz/mxnet,kevinthesun/mxnet,xcgoner/dist-mxnet,stefanhenneking/mxnet,madjam/mxnet,precedenceguo/mxnet,gautamkmr/incubator-mxnet,Mega-DatA-Lab/mxnet,kkk669/mxnet,crazy-cat/incubator-mxnet,weleen/mxnet,EvanzzzZ/mxnet,indhub/mxnet,xcgoner/dist-mxnet,arikpoz/mxnet,thirdwing/mxnet,tornadomeet/mxnet,smolix/incubator-mxnet,crazy-cat/incubator-mxnet,leezu/mxnet,ForkedReposBak/mxnet,sxjscience/mxnet,jiajiechen/mxnet,yuruofeifei/mxnet,LinkHS/incubator-mxnet,tlby/mxnet,saurabh3949/mxnet,stefanhenneking/mxnet,antoan2/incubator-mxnet,coder-james/mxnet,yajiedesign/mxnet,stefanhenneking/mxnet,hpi-xnor/BMXNet,Mega-DatA-Lab/mxnet,hotpxl/mxnet,Ldpe2G/mxnet,TuSimple/mxnet,sergeykolychev/mxnet,nicklhy/mxnet,ptrendx/mxnet,gautamkmr/incubator-mxnet,zhreshold/mxnet,formath/mxnet,ykim362/mxnet,formath/mxnet,crazy-cat/incubator-mxnet,hpi-xnor/BMXNet,weleen/mxnet,dmlc/mxnet,saurabh3949/mxnet,larroy/mxnet,reminisce/mxnet,Northrend/mxnet,luoyetx/mxnet,hotpxl/mxnet,weleen/mxnet,antoan2/incubator-mxnet,wangyum/mxnet,xcgoner/dist-mxnet,likelyzhao/mxnet,Ldpe2G/mxnet,likelyzhao/mxnet,luoyetx/mxnet,nicklhy/mxnet,hpi-xnor/BMXNet,leezu/mxnet,yajiedesign/mxnet,rahul003/mxnet,tlby/mxnet,wangyum/mxnet,LinkHS/incubator-mxnet,Prasad9/incubator-mxnet,eric-haibin-lin/mxnet,ForkedReposBak/mxnet,dmlc/mxnet,ptrendx/mxnet,CodingCat/mxnet,ptrendx/mxnet,ForkedReposBak/mxnet,yuruofeifei/mxnet,ykim362/mxnet,rishita/mxnet,Northrend/mxnet,larroy/mxnet,Guneet-Dhillon/mxnet,EvanzzzZ/mxnet,arank/mxnet,Mega-DatA-Lab/mxnet,sergeykolychev/mxnet,tornadomeet/mxnet,piiswrong/mxnet,ShownX/incubator-mxnet,rahul003/mxnet,yuruofeifei/mxnet,piiswrong/mxnet,zhreshold/mxnet,Guneet-Dhillon/mxnet,stefanhenneking/mxnet,szha/mxnet,smolix/incubator-mxnet,eric-haibin-lin/mxnet,jiajiechen/mxnet,CodingCat/mxnet,Prasad9/incubator-mxnet,saurabh3949/mxnet,sergeykolychev/mxnet,sergeykolychev/mxnet,likelyzhao/mxnet,antoan2/incubator-mxnet,arikpoz/mxnet,jamesliu/mxnet,rishita/mxnet,jennyzhang0215/incubator-mxnet,stefanhenneking/mxnet,lxn2/mxnet,yajiedesign/mxnet,ptrendx/mxnet,pluskid/mxnet,xcgoner/dist-mxnet,tlby/mxnet,hotpxl/mxnet,indhub/mxnet,reminisce/mxnet,pluskid/mxnet,madjam/mxnet,rishita/mxnet,vikingMei/mxnet,larroy/mxnet,saurabh3949/mxnet,Prasad9/incubator-mxnet,navrasio/mxnet,fullfanta/mxnet,tornadomeet/mxnet,hesseltuinhof/mxnet,weleen/mxnet,arank/mxnet,tlby/mxnet,szha/mxnet,apache/incubator-mxnet,reminisce/mxnet,tlby/mxnet,sxjscience/mxnet,jennyzhang0215/incubator-mxnet,luoyetx/mxnet,hesseltuinhof/mxnet,pluskid/mxnet,tlby/mxnet,arikpoz/mxnet,antoan2/incubator-mxnet,jennyzhang0215/incubator-mxnet,zhreshold/mxnet,hotpxl/mxnet,ptrendx/mxnet,jermainewang/mxnet,smolix/incubator-mxnet,ZihengJiang/mxnet,tlby/mxnet,luoyetx/mxnet,DR08/mxnet,Guneet-Dhillon/mxnet,dmlc/mxnet,madjam/mxnet,Northrend/mxnet,crazy-cat/incubator-mxnet,jiajiechen/mxnet,antoan2/incubator-mxnet,ykim362/mxnet,madjam/mxnet,arikpoz/mxnet,mbaijal/incubator-mxnet,fullfanta/mxnet,TuSimple/mxnet,rishita/mxnet,lxn2/mxnet,yuruofeifei/mxnet,kkk669/mxnet,ZihengJiang/mxnet,Prasad9/incubator-mxnet,apaleyes/mxnet,dmlc/mxnet,Guneet-Dhillon/mxnet,apaleyes/mxnet,rishita/mxnet,fullfanta/mxnet,reminisce/mxnet,danithaca/mxnet,Guneet-Dhillon/mxnet,ptrendx/mxnet,Guneet-Dhillon/mxnet,ForkedReposBak/mxnet,thirdwing/mxnet,leezu/mxnet,nicklhy/mxnet,larroy/mxnet,arikpoz/mxnet,formath/mxnet,fullfanta/mxnet,apaleyes/mxnet,weleen/mxnet,precedenceguo/mxnet,arank/mxnet,CodingCat/mxnet,EvanzzzZ/mxnet,jamesliu/mxnet,danithaca/mxnet,ShownX/incubator-mxnet,kkk669/mxnet,larroy/mxnet,Ldpe2G/mxnet,rahul003/mxnet,mbaijal/incubator-mxnet,hotpxl/mxnet,antoan2/incubator-mxnet,coder-james/mxnet,rishita/mxnet,sxjscience/mxnet,hesseltuinhof/mxnet,weleen/mxnet,leezu/mxnet,hesseltuinhof/mxnet,DickJC123/mxnet,kkk669/mxnet,hotpxl/mxnet,smolix/incubator-mxnet,fullfanta/mxnet,sxjscience/mxnet,coder-james/mxnet,TuSimple/mxnet,ykim362/mxnet,indhub/mxnet,ykim362/mxnet,reminisce/mxnet,hotpxl/mxnet,eric-haibin-lin/mxnet,TuSimple/mxnet,sergeykolychev/mxnet,ptrendx/mxnet,luoyetx/mxnet,antoan2/incubator-mxnet,wangyum/mxnet,luoyetx/mxnet,precedenceguo/mxnet,wangyum/mxnet,hesseltuinhof/mxnet,ShownX/incubator-mxnet,Mega-DatA-Lab/mxnet,Ldpe2G/mxnet,TuSimple/mxnet,saurabh3949/mxnet,jermainewang/mxnet,indhub/mxnet,wangyum/mxnet,zhreshold/mxnet,jermainewang/mxnet,pluskid/mxnet,jennyzhang0215/incubator-mxnet,wangyum/mxnet,crazy-cat/incubator-mxnet,DR08/mxnet,DR08/mxnet,yajiedesign/mxnet,DR08/mxnet,hpi-xnor/BMXNet,thirdwing/mxnet,precedenceguo/mxnet,mbaijal/incubator-mxnet,xcgoner/dist-mxnet,Ldpe2G/mxnet,nicklhy/mxnet,rahul003/mxnet,CodingCat/mxnet,mbaijal/incubator-mxnet,eric-haibin-lin/mxnet,smolix/incubator-mxnet,Mega-DatA-Lab/mxnet,stefanhenneking/mxnet,Ldpe2G/mxnet,ZihengJiang/mxnet,DR08/mxnet,kkk669/mxnet,gautamkmr/incubator-mxnet,fullfanta/mxnet,hotpxl/mxnet,navrasio/mxnet,navrasio/mxnet,yuruofeifei/mxnet,jamesliu/mxnet,zhreshold/mxnet,vikingMei/mxnet,LinkHS/incubator-mxnet,weleen/mxnet,Prasad9/incubator-mxnet,szha/mxnet,yuruofeifei/mxnet,arank/mxnet,gautamkmr/incubator-mxnet,antoan2/incubator-mxnet,navrasio/mxnet,pluskid/mxnet,LinkHS/incubator-mxnet,arank/mxnet,ForkedReposBak/mxnet,jamesliu/mxnet,thirdwing/mxnet,zhreshold/mxnet,ForkedReposBak/mxnet,TuSimple/mxnet,larroy/mxnet,formath/mxnet,arank/mxnet,jiajiechen/mxnet,indhub/mxnet,fullfanta/mxnet,szha/mxnet,yuruofeifei/mxnet,apaleyes/mxnet,precedenceguo/mxnet,jiajiechen/mxnet,jiajiechen/mxnet,solin319/incubator-mxnet,Guneet-Dhillon/mxnet,danithaca/mxnet,leezu/mxnet,eric-haibin-lin/mxnet,thirdwing/mxnet,mbaijal/incubator-mxnet,DickJC123/mxnet,LinkHS/incubator-mxnet,larroy/mxnet,pluskid/mxnet,DickJC123/mxnet,rahul003/mxnet,jennyzhang0215/incubator-mxnet,indhub/mxnet,lxn2/mxnet,rahul003/mxnet,navrasio/mxnet,ptrendx/mxnet,yajiedesign/mxnet,ShownX/incubator-mxnet,dmlc/mxnet,kkk669/mxnet,saurabh3949/mxnet,jermainewang/mxnet,apaleyes/mxnet,pluskid/mxnet,jermainewang/mxnet,sxjscience/mxnet,piiswrong/mxnet,hotpxl/mxnet,Mega-DatA-Lab/mxnet,arank/mxnet,vikingMei/mxnet,likelyzhao/mxnet,Northrend/mxnet,apaleyes/mxnet,lxn2/mxnet,ZihengJiang/mxnet,smolix/incubator-mxnet,saurabh3949/mxnet,piiswrong/mxnet,Ldpe2G/mxnet,apache/incubator-mxnet,jamesliu/mxnet,vikingMei/mxnet,ykim362/mxnet,lxn2/mxnet,thirdwing/mxnet,wangyum/mxnet,CodingCat/mxnet,luoyetx/mxnet,solin319/incubator-mxnet,solin319/incubator-mxnet,kevinthesun/mxnet,TuSimple/mxnet,EvanzzzZ/mxnet,TuSimple/mxnet,jiajiechen/mxnet,leezu/mxnet,madjam/mxnet,piiswrong/mxnet,stefanhenneking/mxnet,apache/incubator-mxnet,coder-james/mxnet,likelyzhao/mxnet,wangyum/mxnet,Guneet-Dhillon/mxnet,coder-james/mxnet,Guneet-Dhillon/mxnet,ForkedReposBak/mxnet,navrasio/mxnet,szha/mxnet,hpi-xnor/BMXNet,ShownX/incubator-mxnet,danithaca/mxnet,kevinthesun/mxnet,lxn2/mxnet,nicklhy/mxnet,ShownX/incubator-mxnet,sxjscience/mxnet,thirdwing/mxnet,sxjscience/mxnet,leezu/mxnet,navrasio/mxnet,piiswrong/mxnet,jermainewang/mxnet,eric-haibin-lin/mxnet,jiajiechen/mxnet,dmlc/mxnet,hpi-xnor/BMXNet,solin319/incubator-mxnet,reminisce/mxnet,leezu/mxnet,saurabh3949/mxnet,hesseltuinhof/mxnet,Prasad9/incubator-mxnet,smolix/incubator-mxnet,ykim362/mxnet,hesseltuinhof/mxnet,coder-james/mxnet,hesseltuinhof/mxnet,apache/incubator-mxnet,apaleyes/mxnet,rahul003/mxnet,EvanzzzZ/mxnet,danithaca/mxnet,thirdwing/mxnet,precedenceguo/mxnet,lxn2/mxnet,wangyum/mxnet,Prasad9/incubator-mxnet,vikingMei/mxnet,apaleyes/mxnet,smolix/incubator-mxnet,Mega-DatA-Lab/mxnet,kevinthesun/mxnet,yajiedesign/mxnet,likelyzhao/mxnet,ShownX/incubator-mxnet,rahul003/mxnet,xcgoner/dist-mxnet,pluskid/mxnet,piiswrong/mxnet,formath/mxnet,danithaca/mxnet,ptrendx/mxnet,reminisce/mxnet,CodingCat/mxnet,EvanzzzZ/mxnet,sergeykolychev/mxnet,Northrend/mxnet,DickJC123/mxnet,fullfanta/mxnet,arikpoz/mxnet,jermainewang/mxnet,vikingMei/mxnet,jennyzhang0215/incubator-mxnet,sxjscience/mxnet,thirdwing/mxnet,DR08/mxnet,navrasio/mxnet,pluskid/mxnet,gautamkmr/incubator-mxnet,mbaijal/incubator-mxnet,coder-james/mxnet,EvanzzzZ/mxnet,sxjscience/mxnet,LinkHS/incubator-mxnet,TuSimple/mxnet,likelyzhao/mxnet,tornadomeet/mxnet,coder-james/mxnet,Prasad9/incubator-mxnet,vikingMei/mxnet,tlby/mxnet,reminisce/mxnet,tornadomeet/mxnet,ZihengJiang/mxnet,Mega-DatA-Lab/mxnet,jamesliu/mxnet,gautamkmr/incubator-mxnet,nicklhy/mxnet,danithaca/mxnet,arikpoz/mxnet,rishita/mxnet,madjam/mxnet,indhub/mxnet,ForkedReposBak/mxnet,kkk669/mxnet,xcgoner/dist-mxnet,CodingCat/mxnet,jennyzhang0215/incubator-mxnet,tornadomeet/mxnet,jennyzhang0215/incubator-mxnet,EvanzzzZ/mxnet,larroy/mxnet,lxn2/mxnet,mbaijal/incubator-mxnet,szha/mxnet,ykim362/mxnet,indhub/mxnet,zhreshold/mxnet,solin319/incubator-mxnet,danithaca/mxnet,dmlc/mxnet,kevinthesun/mxnet,nicklhy/mxnet,lxn2/mxnet,EvanzzzZ/mxnet,solin319/incubator-mxnet,fullfanta/mxnet,indhub/mxnet,yajiedesign/mxnet,coder-james/mxnet,gautamkmr/incubator-mxnet,hpi-xnor/BMXNet,jermainewang/mxnet,saurabh3949/mxnet,weleen/mxnet,Northrend/mxnet,formath/mxnet,madjam/mxnet,ForkedReposBak/mxnet,Northrend/mxnet,arank/mxnet,Ldpe2G/mxnet,sergeykolychev/mxnet,piiswrong/mxnet