Work on moving Document into its own wrapper

demo/35-hyperlinks.ts

@@ -1,13 +1,31 @@
 // Example on how to add hyperlinks to websites
 // Import from 'docx' rather than '../build' if you install from npm
 import * as fs from "fs";
-import { ExternalHyperlink, Document, Packer, Paragraph, Media, TextRun } from "../build";
+import { ExternalHyperlink, Document, Packer, Paragraph, Media, TextRun, Footer } from "../build";
 
 const doc = new Document({});
 
 const image1 = Media.addImage(doc, fs.readFileSync("./demo/images/image1.jpeg"));
 
 doc.addSection({
+    footers: {
+        default: new Footer({
+            children: [
+                new Paragraph({
+                    children: [
+                        new TextRun("Click here for the "),
+                        new ExternalHyperlink({
+                            child: new TextRun({
+                                text: "Footer external hyperlink",
+                                style: "Hyperlink",
+                            }),
+                            link: "http://www.example.com",
+                        }),
+                    ],
+                }),
+            ],
+        }),
+    },
     children: [
         new Paragraph({
             children: [