MAJ README.md for ISingleton usage

README.md

@@ -13,9 +13,10 @@ composer require jrosset/singleton
 ```php
 <?php
 
+use jrosset\Singleton\ISingleton;
 use jrosset\Singleton\TSingleton;
 
-class MyClass {
+class MyClass implements ISingleton {
     use TSingleton;
    
     protected function __construct() {}