Update step-26-mock-server-configuration-typescript-3e1c64f.md (#154)

The config method is a static method, which means it's a property of the class itself, not an instance of the class. We can access it using MockServer.config instead of mockServer.config.

docs/03_Get-Started/step-26-mock-server-configuration-typescript-3e1c64f.md

@@ -161,7 +161,7 @@ export default {
         const urlParams = new URLSearchParams(window.location.search);
 
         // configure mock server with a delay
-        mockServer.config({
+        MockServer.config({
             autoRespond: true,
             autoRespondAfter: parseInt(urlParams.get("serverDelay") || "500")
         });