feat: API docs for service api (#24425)

Signed-off-by: -LAN- <laipz8200@outlook.com>

api/controllers/service_api/index.py

@@ -1,9 +1,10 @@
 from flask_restx import Resource
 
 from configs import dify_config
-from controllers.service_api import api
+from controllers.service_api import service_api_ns
 
 
+@service_api_ns.route("/")
 class IndexApi(Resource):
     def get(self):
         return {
@@ -11,6 +12,3 @@ class IndexApi(Resource):
             "api_version": "v1",
             "server_version": dify_config.project.version,
         }
-
-
-api.add_resource(IndexApi, "/")