[MXNET-23] add README for test directory (#11390)
[MXNET-23] add README for test directory (#11390)

* add README for tests

* update read me with relative path to test file

* update test readme to include instructions for running with docker

* retrigger

* another retrigger

zhreshold/mxnet,jamesliu/mxnet,eric-haibin-lin/mxnet,ForkedReposBak/mxnet,indhub/mxnet,rahul003/mxnet,precedenceguo/mxnet,ptrendx/mxnet,leezu/mxnet,indhub/mxnet,mbaijal/incubator-mxnet,jamesliu/mxnet,larroy/mxnet,yajiedesign/mxnet,ptrendx/mxnet,tlby/mxnet,zhreshold/mxnet,tlby/mxnet,leezu/mxnet,indhub/mxnet,ptrendx/mxnet,dmlc/mxnet,ForkedReposBak/mxnet,mbaijal/incubator-mxnet,rahul003/mxnet,sxjscience/mxnet,rahul003/mxnet,sxjscience/mxnet,ptrendx/mxnet,leezu/mxnet,indhub/mxnet,szha/mxnet,larroy/mxnet,precedenceguo/mxnet,jamesliu/mxnet,reminisce/mxnet,ptrendx/mxnet,rahul003/mxnet,yajiedesign/mxnet,ForkedReposBak/mxnet,eric-haibin-lin/mxnet,zhreshold/mxnet,rahul003/mxnet,sxjscience/mxnet,eric-haibin-lin/mxnet,ptrendx/mxnet,zhreshold/mxnet,ForkedReposBak/mxnet,precedenceguo/mxnet,mbaijal/incubator-mxnet,dmlc/mxnet,indhub/mxnet,DickJC123/mxnet,larroy/mxnet,eric-haibin-lin/mxnet,szha/mxnet,yajiedesign/mxnet,rahul003/mxnet,navrasio/mxnet,reminisce/mxnet,sxjscience/mxnet,mbaijal/incubator-mxnet,navrasio/mxnet,reminisce/mxnet,larroy/mxnet,leezu/mxnet,szha/mxnet,DickJC123/mxnet,jamesliu/mxnet,apache/incubator-mxnet,navrasio/mxnet,szha/mxnet,leezu/mxnet,tlby/mxnet,leezu/mxnet,jamesliu/mxnet,tlby/mxnet,reminisce/mxnet,szha/mxnet,precedenceguo/mxnet,sxjscience/mxnet,leezu/mxnet,apache/incubator-mxnet,dmlc/mxnet,mbaijal/incubator-mxnet,zhreshold/mxnet,reminisce/mxnet,navrasio/mxnet,jamesliu/mxnet,ForkedReposBak/mxnet,ForkedReposBak/mxnet,ptrendx/mxnet,reminisce/mxnet,jamesliu/mxnet,ForkedReposBak/mxnet,dmlc/mxnet,dmlc/mxnet,zhreshold/mxnet,jamesliu/mxnet,mbaijal/incubator-mxnet,mbaijal/incubator-mxnet,tlby/mxnet,dmlc/mxnet,dmlc/mxnet,ForkedReposBak/mxnet,reminisce/mxnet,leezu/mxnet,yajiedesign/mxnet,rahul003/mxnet,DickJC123/mxnet,szha/mxnet,indhub/mxnet,navrasio/mxnet,eric-haibin-lin/mxnet,eric-haibin-lin/mxnet,eric-haibin-lin/mxnet,tlby/mxnet,mbaijal/incubator-mxnet,tlby/mxnet,indhub/mxnet,tlby/mxnet,dmlc/mxnet,sxjscience/mxnet,yajiedesign/mxnet,indhub/mxnet,zhreshold/mxnet,eric-haibin-lin/mxnet,navrasio/mxnet,precedenceguo/mxnet,yajiedesign/mxnet,indhub/mxnet,tlby/mxnet,reminisce/mxnet,eric-haibin-lin/mxnet,zhreshold/mxnet,ForkedReposBak/mxnet,larroy/mxnet,rahul003/mxnet,sxjscience/mxnet,DickJC123/mxnet,ptrendx/mxnet,navrasio/mxnet,ptrendx/mxnet,apache/incubator-mxnet,szha/mxnet,larroy/mxnet,ptrendx/mxnet,larroy/mxnet,yajiedesign/mxnet,dmlc/mxnet,apache/incubator-mxnet,zhreshold/mxnet,szha/mxnet,rahul003/mxnet,larroy/mxnet,precedenceguo/mxnet,szha/mxnet,mbaijal/incubator-mxnet,larroy/mxnet,tlby/mxnet,jamesliu/mxnet,precedenceguo/mxnet,navrasio/mxnet,sxjscience/mxnet,precedenceguo/mxnet,yajiedesign/mxnet,precedenceguo/mxnet,sxjscience/mxnet,yajiedesign/mxnet,navrasio/mxnet,reminisce/mxnet,reminisce/mxnet,leezu/mxnet