Update welcome-to-serverless.mdx to force a build

This is a non-visible change to indicate that the new build pipeline is successful and live on https://www.elastic.co/docs. Safe to merge this once out of draft

serverless/pages/welcome-to-serverless.mdx

@@ -80,3 +80,7 @@ Choose the type of project that matches your needs and we’ll help you get star
     },
   ]}
 />
+
+
+<div className="docs-migration-test" data-comment="This element is safe to delete for any future contributor. Used for testing only" />
+