Added documentation on lazy data

Author: Fa-BRAIK

docs/LazyData.md

@@ -0,0 +1,50 @@
+Lazy Data
+=
+
+Out of the box, extending `Data` will give you the ability to create [Lazy objects](https://www.php.net/manual/en/language.oop5.lazy-objects.php).
+You can achieve that by calling either `createLazy` or `createLazyUsing` methods, depending
+on whether you want to pass properties from the get-go or not.
+
+Let's take for example `UserData` class:
+
+```php
+use Nuxtifyts\PhpDto\Data;
+
+final readonly class UserData extends Data
+{
+    public function __construct(
+        public int $id,
+        public string $firstName,
+        public string $lastName
+    ) {}
+}
+```
+
+We can create a lazy object like this:
+
+```php
+$user = UserData::createLazy(
+    id: 1, 
+    firstName: 'John', 
+    lastName: 'Doe'
+);
+```
+
+Or, if we have more complex logic to run before creating the object, we can do:
+
+```php
+// Supposedly, we know the user id.
+$userId = 1;
+
+$user = UserData::createLazyUsing(
+    static function () use($userId): UserData {
+        // Fetch user data from the database. then create the DTO.
+        return UserData::from(UserModel::find($userId));
+    }
+)
+```
+
+The `createLazyUsing` method accepts a closure that returns the object. 
+This closure will be called only once, and the object will be cached for future calls.
+
+> For more information about lazy objects. Please refer to the [PHP documentation](https://www.php.net/manual/en/language.oop5.lazy-objects.php).