Add header objects and demo

src/file/document/body/section-properties/header-reference/header-reference.ts

@@ -0,0 +1,14 @@
+import { XmlComponent } from "file/xml-components";
+import { HeaderReferenceAttributes } from "./header-reference-attributes";
+
+export class HeaderReference extends XmlComponent {
+    constructor() {
+        super("w:headerReference");
+        this.root.push(
+            new HeaderReferenceAttributes({
+                type: "default",
+                id: `rId${3}`,
+            }),
+        );
+    }
+}