Revert "Revert "ensure that Katacoda won't try to load before the page content" (#1093)" (#1099)

This reverts commit 6c6b9a2 [formerly 9998a1c].

Former-commit-id: bae1430

Author: josh-heyer

src/components/katacoda-panel.js

@@ -133,7 +133,10 @@ const KatacodaPanel = ({ katacodaPanelData }) => {
   return (
     <>
       <Helmet>
-        <script src="https://katacoda.com/embed.js" />
+        <script
+          src="https://katacoda.com/embed.js"
+          data-katacoda-ondemand="true"
+        />
       </Helmet>
 
       {isShown ? (