Adding a Settings link to your plugin settings page.

add-settings-link-to-wordpress-plugin.php

<?php 

//adding settings link to wordpress plugin

add_filter('plugin_action_links_'.plugin_basename(__FILE__), 'njengah_admin_page_settings_link');
 
function njengah_admin_page_settings_link( $links ) {
	$links[] = '<a href="' .
		admin_url( 'admin.php?page=njengah_admin_page' ) . // replace this with your admin page
		'">' . __('Settings') . '</a>';
	return $links;
}