Added more info around filter objects in README.md
Added more info around filter objects in README.md

ExactTarget/Fuel-Node-SOAP,jimmyburgess91/uber-import-soap,nlf/Fuel-Node-SOAP,Rebelmail/FuelSDK-Node-SOAP,salesforcefuel/FuelSDK-Node-SOAP,jimmyburgess/fuel-soap-client-retrieve