Docs for MXRecordIO, MXIndexedRecordIO modified (#6013)
Docs for MXRecordIO, MXIndexedRecordIO modified (#6013)

* docs for MXIndexedRecordIO modified

* changes after review

* recordIO doc modified

* changes after review

* lint error

* minor change

* minor change after review

* empty commit to retrigger build

* changes after review

Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet,Guneet-Dhillon/mxnet