Made demo files into typescript files

demo/demo15.ts

@@ -0,0 +1,18 @@
+// Page break before example
+// 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");
+const paragraph2 = new Paragraph("Hello World on another page").pageBreakBefore();
+
+doc.addParagraph(paragraph);
+doc.addParagraph(paragraph2);
+
+const packer = new Packer();
+
+packer.toBuffer(doc).then((buffer) => {
+    fs.writeFileSync("My Document.docx", buffer);
+});