docs: Add checklist item to all blocks example (#762)

Author: matthewlipski

examples/01-basic/03-all-blocks/App.tsx

@@ -40,6 +40,10 @@ export default function App() {
         type: "numberedListItem",
         content: "Numbered List Item",
       },
+      {
+        type: "checkListItem",
+        content: "Check List Item",
+      },
       {
         type: "table",
         content: {