Add note about using protocol v3 with nested collections
Add note about using protocol v3 with nested collections

thobbs/python-driver,datastax/python-driver,kishkaru/python-driver,sontek/python-driver,yi719/python-driver,jregovic/python-driver,jfelectron/python-driver,sontek/python-driver,HackerEarth/cassandra-python-driver,HackerEarth/cassandra-python-driver,tempbottle/python-driver,beobal/python-driver,bbirand/python-driver,stef1927/python-driver,yi719/python-driver,coldeasy/python-driver,kracekumar/python-driver,bbirand/python-driver,vipjml/python-driver,tempbottle/python-driver,thobbs/python-driver,thelastpickle/python-driver,markflorisson/python-driver,mambocab/python-driver,kracekumar/python-driver,vipjml/python-driver,mike-tr-adamson/python-driver,mike-tr-adamson/python-driver,mobify/python-driver,mobify/python-driver,coldeasy/python-driver,jregovic/python-driver,thelastpickle/python-driver,mambocab/python-driver,beobal/python-driver,markflorisson/python-driver,jfelectron/python-driver,datastax/python-driver,stef1927/python-driver,kishkaru/python-driver