fix code block error (#539)

add a comma to code block to make it work

Co-authored-by: Peter Doggart <[email protected]>

Author: Zhilinlinlin

doc/scaling.rst

@@ -243,7 +243,7 @@ Each `apivX` module will have the following pattern:
     from .apis.namespaceX import api as nsX
 
     blueprint = Blueprint('api', __name__, url_prefix='/api/1')
-    api = Api(blueprint
+    api = Api(blueprint,
         title='My Title',
         version='1.0',
         description='A description',