Added notice about frequency estimation / Count-Min Sketch to README
Added notice about frequency estimation / Count-Min Sketch to README

smartpcr/stream-lib,tempbottle/stream-lib,oertl/stream-lib,orneryhippo/stream-lib,joychugh/stream-lib,oertl/stream-lib,orneryhippo/stream-lib,tempbottle/stream-lib,cykl/stream-lib,smartpcr/stream-lib,joychugh/stream-lib,cykl/stream-lib