update form in a modal doc

Author: miljan-aleksic

src/essentials-for-yootheme-pro/addons/forms/form-in-a-modal.md

@@ -2,6 +2,7 @@
 
 Out of the box, a form cannot be displayed in a Modal, but there are 3rd party solutions.
 
+- [FS Modal](https://flart.studio/yootheme-pro/modal) by Flart Studio
 - [FS Teaser Card](https://flart.studio/yootheme-pro/teaser-card) by Flart Studio
 - [DJ-Popup](https://dj-extensions.com/yootheme/dj-popup) by DJ Extensions
 - [JP CE Modal Pro](https://extensions.joomlapro.com/product/ce-modal-pro) by JoomlaPro