updated README.rst for the information that reading from webhdfs is already supported
updated README.rst for the information that reading from webhdfs is already supported

gojomo/smart_open,RaRe-Technologies/smart_open,mpenkov/smart_open,piskvorky/smart_open,asieira/smart_open,nvie/smart_open,RaRe-Technologies/smart_open,val314159/smart_open,mpenkov/smart_open