DOC/API: Remove limit and improve docstring.
DOC/API: Remove limit and improve docstring.

ericdill/datamuxer,danielballan/datamuxer,danielballan/datamuxer,tacaswell/dataportal,danielballan/dataportal,ericdill/databroker,tacaswell/dataportal,ericdill/datamuxer,NSLS-II/dataportal,danielballan/dataportal,ericdill/databroker,NSLS-II/datamuxer,NSLS-II/dataportal