Made demo files into typescript files

demo/demo4.ts

@@ -0,0 +1,15 @@
+// Example of how you would create a table and add data to it
+// 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 table = doc.createTable(4, 4);
+table.getCell(2, 2).addContent(new Paragraph("Hello"));
+
+const packer = new Packer();
+
+packer.toBuffer(doc).then((buffer) => {
+    fs.writeFileSync("My Document.docx", buffer);
+});