Fix example code in README.md

Function `searchUris` takes an object with `uri` field which is a string and a `threatTypes` field which is array of numbers, not strings.

README.md

@@ -63,14 +63,18 @@ npm install @google-cloud/web-risk
  */
 async function quickstart(uri) {
   // Create the WebRisk client library.
-  const {WebRiskServiceClient} = require('@google-cloud/web-risk');
+  const {WebRiskServiceClient, protos} = require('@google-cloud/web-risk');
   const client = new WebRiskServiceClient();
 
   // Create an API request to check for malware, social engineering,
   // and unwanted software.
   const request = {
     uri: uri,
-    threatTypes: ['MALWARE', 'SOCIAL_ENGINEERING', 'UNWANTED_SOFTWARE'],
+    threatTypes: [
+      protos.google.cloud.webrisk.v1.ThreatType.MALWARE,
+      protos.google.cloud.webrisk.v1.ThreatType.SOCIAL_ENGINEERING,
+      protos.google.cloud.webrisk.v1.ThreatType.UNWANTED_SOFTWARE,
+    ],
   };
 
   // call the WebRisk searchUris API.