Favicon
All websites need a favicon, if only to stop the browser having to download a 404 page.
By default you should save it to:
/app/public/a/img/global/favicon.ico
This will be served by the framework when a request is made to:
https://www.example.com/favicon.ico
The path to this file can be changed with:
$config['output.favicon_path'] = '/full/path/to/favicon.ico';
This configuration value cannot be set in /app/library/setup/setup.php, as that file often makes database queries, and opens a session, which should not be necessary to quickly serve up a simple file.
If you want to tell the browser to get the favicon from somewhere else, set:
$config['output.favicon_url'] = '/url/to/favicon.ico';
Where it will use this value in the link tag in the html response:
<link rel="shortcut icon" type="image/x-icon" href="/url/to/favicon.ico" />
This configuration value can be set in /app/library/setup/setup.php.