docs: Add more complete stream download example (#645)

* Add more complete stream download example

* Change header size

Co-authored-by: Antoni Kepinski <xxczaki@pm.me>

README.md

@@ -267,18 +267,21 @@ Cookies are not stored by default. However, cookies can be extracted and passed
 
 ### Streams
 
-The "Node.js way" is to use streams when possible:
+The "Node.js way" is to use streams when possible. You can pipe `res.body` to another stream. This example uses [stream.pipeline](https://nodejs.org/api/stream.html#stream_stream_pipeline_streams_callback) to attach stream error handlers and wait for the download to complete.
 
 ```js
-const {createWriteStream} = require('fs');
-const fetch = require('node-fetch');
+const util = require('util');
+const fs = require('fs');
+const streamPipeline = util.promisify(require('stream').pipeline);
 
-fetch(
-	'https://octodex.github.com/images/Fintechtocat.png'
-).then(res => {
-	const dest = fs.createWriteStream('./octocat.png');
-	res.body.pipe(dest);
-});
+fetch('https://assets-cdn.github.com/images/modules/logos_page/Octocat.png')
+	.then(res => {
+		if (!res.ok) {
+			throw new Error(`unexpected response ${res.statusText}`);
+		}
+
+		return streamPipeline(res.body, fs.createWriteStream('./octocat.png'));
+	});
 ```
 
 ### Buffer