chore: create and add plugin template

created with help by these Websites:
[Delicious Brains](https://deliciousbrains.com/wordpress-plugin-development-template-files/)
[Wordpress Plugin Boilerplate generator](https://wppb.me/)

rk-wichteln/includes/class-rk-wichteln-activator.php

@@ -0,0 +1,36 @@
+<?php
+
+/**
+ * Fired during plugin activation
+ *
+ * @link       https://wpdev.rainer-kehnen.de
+ * @since      1.0.0
+ *
+ * @package    Rk_Wichteln
+ * @subpackage Rk_Wichteln/includes
+ */
+
+/**
+ * Fired during plugin activation.
+ *
+ * This class defines all code necessary to run during the plugin's activation.
+ *
+ * @since      1.0.0
+ * @package    Rk_Wichteln
+ * @subpackage Rk_Wichteln/includes
+ * @author     Rainer Kehnen <wpdev.plugin@rainer-kehnen.de>
+ */
+class Rk_Wichteln_Activator {
+
+	/**
+	 * Short Description. (use period)
+	 *
+	 * Long Description.
+	 *
+	 * @since    1.0.0
+	 */
+	public static function activate() {
+
+	}
+
+}