Fixed docblock opener

It's important for tools relying on docblock types to perform static analysis (think phan, phpstan, psalm, etc)

src/Entities/Traits/EntityTrait.php

@@ -11,7 +11,7 @@ namespace League\OAuth2\Server\Entities\Traits;
 
 trait EntityTrait
 {
-    /*
+    /**
      * @var string
      */
     protected $identifier;