How to replace file_get_contents() with a WordPress Filesystem call

I’m using the PHP file_get_contents() function to retrieve and echo the contents of an SVG-file.

I checked the theme with the WordPress.org theme checker and I am currently resolving all the issues. One of the issues is the use of file_get_contents.

It gives me the following warning:

I tried finding information about the $wp_filesystem thing, but there is very little information available and even less examples (to be honest, I’m not totally sure if that’s the correct function to use).

How can I use a WordPress function to retrieve a file and echo the contents of it in a PHP-file?

I’m really at loss what I should do with this. All help is very much appreciated!