Made demo files into typescript files

demo/demo7.ts

@@ -0,0 +1,18 @@
+// Example of how to set the document to landscape
+// Import from 'docx' rather than '../build' if you install from npm
+import * as fs from "fs";
+import { Document, Packer, PageOrientation, Paragraph } from "../build";
+
+const doc = new Document(undefined, {
+    orientation: PageOrientation.LANDSCAPE,
+});
+
+const paragraph = new Paragraph("Hello World");
+
+doc.addParagraph(paragraph);
+
+const packer = new Packer();
+
+packer.toBuffer(doc).then((buffer) => {
+    fs.writeFileSync("My Document.docx", buffer);
+});