[Reviewed] [Panel sprite button] Add a link to the asset pack in the description. (#714)

* Don't show in changelog.

Author: D8H

extensions/reviewed/PanelSpriteButton.json

@@ -9,7 +9,11 @@
   "previewIconUrl": "https://resources.gdevelop-app.com/assets/Icons/Line Hero Pack/Master/SVG/Interface Elements/Interface Elements_interface_ui_button_ok_cta_clock_tap.svg",
   "shortDescription": "A button that can be customized.",
   "version": "1.2.0",
-  "description": "The button can be customized with a background for each state and a label. It handles user interactions and a simple condition can be used to check if it is clicked.",
+  "description": [
+    "The button can be customized with a background for each state and a label. It handles user interactions and a simple condition can be used to check if it is clicked.",
+    "",
+    "There are ready-to-use buttons in the asset-store [menu buttons pack](https://editor.gdevelop.io/?initial-dialog=asset-store&asset-pack=menu-buttons-menu-buttons)."
+  ],
   "origin": {
     "identifier": "PanelSpriteButton",
     "name": "gdevelop-extension-store"