Update WDS trainer guide - Serverless architecture.md

Fixing logo link.

Whiteboard design session/WDS trainer guide - Serverless architecture.md

@@ -1,4 +1,4 @@
-![Microsoft Cloud Workshops](https://github.com/Microsoft/MCW-Template-Cloud-Workshop/raw/master/Media/ms-cloud-workshop.png 'Microsoft Cloud Workshops')
+![Microsoft Cloud Workshops](https://github.com/Microsoft/MCW-Template-Cloud-Workshop/raw/main/Media/ms-cloud-workshop.png 'Microsoft Cloud Workshops')
 
 <div class="MCWHeader1">
 Serverless architecture