Add title support using YAML frontmatter

cypress/integration/rendering/stateDiagram-v2.spec.js

@@ -559,4 +559,16 @@ stateDiagram-v2
       );
     });
   });
+  it('1433: should render a simple state diagram with a title', () => {
+    imgSnapshotTest(
+      `---
+       title: simple state diagram
+       ---
+       stateDiagram-v2
+       [*] --> State1
+       State1 --> [*]
+      `,
+      {}
+    );
+  });
 });