add documentation about the new match_querystring feature
add documentation about the new match_querystring feature

Multiposting/HTTPretty,pxg/HTTPretty,demianbrecht/HTTPretty,Multiposting/HTTPretty,pxg/HTTPretty,letolab/HTTPretty,BenjamenMeyer/HTTPretty,codepython/HTTPretty,xgess/HTTPretty,andresriancho/HTTPretty,codepython/HTTPretty,andresriancho/HTTPretty,paylogic/HTTPretty,andresriancho/HTTPretty,gabrielfalcao/HTTPretty,codepython/HTTPretty,xgess/HTTPretty,paylogic/HTTPretty,gabrielfalcao/HTTPretty,demianbrecht/HTTPretty,letolab/HTTPretty,demianbrecht/HTTPretty,andresriancho/HTTPretty,paylogic/HTTPretty,pxg/HTTPretty,letolab/HTTPretty,xgess/HTTPretty,BenjamenMeyer/HTTPretty,Multiposting/HTTPretty,BenjamenMeyer/HTTPretty