Update 04 Thresholds.md

Correct discrepancy between 200ms (comment) and 500ms (actual code) to be 200ms on both.

Author: reub-the-cube

src/data/markdown/docs/01 guides/02 Using k6/04 Thresholds.md

@@ -28,7 +28,7 @@ import http from 'k6/http';
 export let options = {
   thresholds: {
     http_req_failed: ['rate<0.01'],   // http errors should be less than 1% 
-    http_req_duration: ['p(95)<500'], // 95% of requests should be below 200ms
+    http_req_duration: ['p(95)<200'], // 95% of requests should be below 200ms
   },
 };