WordPress developers do many custom things with their plugins and themes above the basic functionality available at WordPress Codex. Adding a plugin settings link in the plugin page just beneath your plugin could be one of those pretty custom things. If you don’t know what I’m saying, have a look at highlighted sections in the below screenshot:

I did a quick research and found this cool snippet that lets you add the plugin settings page link beneath your plugin on the plugins page in WordPress.

function my_plugin_settings_link($links) { 
  $settings_link = '<a href="options-general.php?page=plugin-options.php">Settings</a>'; 
  array_unshift($links, $settings_link); 
  return $links; 
}
$plugin = plugin_basename(__FILE__); 
add_filter("plugin_action_links_$plugin", 'my_plugin_settings_link' );

Just add the above code to your plugin PHP file, and don’t forget to replace the text in green to your plugin settings file.