docs: add JSON Assets Demo example to showcase policy loading from external JSON files

Author: dgarciasquare1

docs.json

@@ -40,6 +40,11 @@
           "href": "/examples/basic-policy-demo",
           "icon": "code"
         },
+        {
+          "title": "JSON Assets Demo",
+          "href": "/examples/json-assets-demo",
+          "icon": "file-text"
+        },
         {
           "title": "Role Management Demo",
           "href": "/examples/role-management-demo",