[IDP-46] Display Postmark Docs (#19817)

Author: Wyrine

postmark/manifest.json

@@ -2,7 +2,7 @@
   "manifest_version": "2.0.0",
   "app_uuid": "1af07d08-4c45-43f1-9fef-4c2653d1a0b8",
   "app_id": "postmark",
-  "display_on_public_website": false,
+  "display_on_public_website": true,
   "tile": {
     "overview": "README.md#Overview",
     "configuration": "README.md#Setup",