Fix the typo in PHPDoc comment

Author: dmytro-ch

app/code/Magento/Backend/Model/Config/SessionLifetime/BackendModel.php

@@ -16,14 +16,17 @@
  */
 class BackendModel extends Value
 {
-    /** Maximum dmin session lifetime; 1 year*/
+    /** Maximum admin session lifetime; 1 year*/
     const MAX_LIFETIME = 31536000;
 
     /** Minimum admin session lifetime */
     const MIN_LIFETIME = 60;
 
     /**
+     * Processing object before save data
+     *
      * @since 100.1.0
+     * @throws LocalizedException
      */
     public function beforeSave()
     {