Displaying a help page

A colleague gave me the following code to add a Help page to the admin menu (so that clients can add content themselves). It involves adding code to functions.php. Obviously every time I upgrade my theme I lose this bit of code. I could create a child theme but Code Snippets was recommended. So I’ve added the following code in Code Snippets:

include_once( '../../functions/leedspff-help.php' );

but the help file isn’t displaying.
This is the absolute path to the leedspff-help.php file – https://dev.leedspff.org.uk/htdocs/wp-content/functions/leedspff-help.php

Obviously I’ve done something both stupid and probably quite easy to fix, so if anyone has any thoughts I’d be very very grateful!

/* Put this in functions/leedspff-help.php */

<?php
add_action('admin_menu', function(){
        add_menu_page( 'LeedsPFF Help', 'LeedsPFF Help', 'administrator', __FILE__, 'display_leedspff_help', '', 30 );
});

function display_leedspff_help(){?>
       <h2>LeedsPFF Help</h2>
<?php
                    $help_text = get_post( 176 );
            // Don't apply filter so that shortcodes remain as text
            //$help_text = apply_filters( 'the_content', $help_text->post_content );
            $help_text = wpautop( $help_text->post_content );
            echo $help_text;
       
  }