Add Express packer deprecation warning

docs/usage/packers.md

@@ -32,21 +32,32 @@ const docx = require("docx");
 
 const doc = new docx.Document();
 const exporter = new docx.StreamPacker(doc);
-const buffer = exporter.pack();
+const stream = exporter.pack();
 ```
 
 ## Express Packer
 
+The old express packer is now deprecated and may disappear soon, so you should upgrade.
+
+The reason for this is because it means this project needs to know about and use `express`, which for a Word document generator, does not sound right. Seperation of concerns.
+
+It will still be usable (for now), but it is ill advised.
+
 I used the express exporter in my [website](http://www.dolan.bio).
 
-Pass in the necessary parameters:
+The recommended way is to use the `StreamPacker` and handle the `express` magic outside of the library:
 
 ```js
 const docx = require("docx");
 
 const doc = new docx.Document();
-const exporter = new docx.ExpressPacker(doc, res);
-exporter.pack("My Document");
+const exporter = new docx.StreamPacker(doc);
+
+const stream = exporter.pack();
+
+// Express' response object
+res.attachment('yourfile.xlsx');
+stream.pipe(res);
 ```
 
 where `res` is the response object obtained through the Express router. It is that simple. The file will begin downloading in the browser.

src/export/packer/express.ts

@@ -4,6 +4,9 @@ import { File } from "file";
 import { Compiler } from "./compiler";
 import { IPacker } from "./packer";
 
+/**
+ * @deprecated ExpressPacker is now deprecated. Please use the StreamPacker instead and pipe that to `express`' `res` object
+ */
 export class ExpressPacker implements IPacker {
     private readonly packer: Compiler;