Add openapi-serialize project to related projects list (#1518)

docs/related-projects.md

@@ -19,7 +19,8 @@ sidebar: false
 | [OpenAPI-Symfony-Routing][11] | Load routes in Symfony based on OpenAPI annotations       |
 | [Swag It PHP][12]             | Convert JSON to PHP Swagger annotations                   |
 | [Laravel Swagger][13]         | OpenApi or Swagger integration to Laravel                 |
-| [openapi-extras][14]          | Extra annotations for php-swagger                         |
+| [openapi-extras][14]          | Extra annotations for swagger-php                         |
+| [openapi-serialize][15]       | Serialize an object using swagger-php                     |
 
 Is a related project missing? Create a pull request!
 
@@ -37,3 +38,4 @@ Is a related project missing? Create a pull request!
 [12]: https://kizu514.com/swagit.php
 [13]: https://github.com/DarkaOnLine/L5-Swagger
 [14]: https://github.com/DerManoMann/openapi-extras
+[15]: https://github.com/MattyRad/openapi-serialize