Add import to node-writing-files.en.md (#2730)

lopezac · ovflowd · web-flow · commit ebb1489809fe · 2022-09-09T13:43:04.000+02:00
Co-authored-by: Claudio Wunder &lt;cwunder@gnome.org&gt;
diff --git a/content/learn/node-writing-files.en.md b/content/learn/node-writing-files.en.md
@@ -76,6 +76,8 @@ The flags you'll likely use are
 A handy method to append content to the end of a file is `fs.appendFile()` (and its `fs.appendFileSync()` counterpart):
 
 ```js
+const fs = require('fs');
+
 const content = 'Some content!';
 
 fs.appendFile('file.log', content, err => {
