docs: fix typo in first example in readme (watson-developer-cloud#1003)

Author: MasterOdin

README.md

@@ -78,7 +78,7 @@ import DiscoveryV1 from 'ibm-watson/discovery/v1';
 import { IamAuthenticator } from 'ibm-watson/auth';
 
 const discoveryClient = new DiscoveryV1({
-  authenticator: new IamAuthenticator({ apikey: '{apikey}' })
+  authenticator: new IamAuthenticator({ apikey: '{apikey}' }),
   version: '{version}',
 });