Merge pull request pallets#2843 from gcrsaldanha/use-set-literal-in-docs

🎨 Use set literal instead of set method in file uploading example

Author: davidism

docs/patterns/fileuploads.rst

@@ -25,7 +25,7 @@ bootstrapping code for our application::
     from werkzeug.utils import secure_filename
 
     UPLOAD_FOLDER = '/path/to/the/uploads'
-    ALLOWED_EXTENSIONS = set(['txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif'])
+    ALLOWED_EXTENSIONS = {'txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif'}
 
     app = Flask(__name__)
     app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER