Made demo files into typescript files

demo/demo17.ts

@@ -0,0 +1,21 @@
+// Footnotes
+// Import from 'docx' rather than '../build' if you install from npm
+import * as fs from "fs";
+import { Document, Packer, Paragraph } from "../build";
+
+const doc = new Document();
+
+const paragraph = new Paragraph("Hello World").referenceFootnote(1);
+const paragraph2 = new Paragraph("Hello World").referenceFootnote(2);
+
+doc.addParagraph(paragraph);
+doc.addParagraph(paragraph2);
+
+doc.createFootnote(new Paragraph("Test"));
+doc.createFootnote(new Paragraph("My amazing reference"));
+
+const packer = new Packer();
+
+packer.toBuffer(doc).then((buffer) => {
+    fs.writeFileSync("My Document.docx", buffer);
+});