readme: fix erroneous service instantiation
readme: fix erroneous service instantiation

jsonws.api('1.0.0', 'test api') throws 'TypeError: jsonws.api is not a function'
ChaosGroup/json-ws,ChaosGroup/json-ws,ChaosGroup/json-ws,ChaosGroup/json-ws,ChaosGroup/json-ws,ChaosGroup/json-ws