doc reqcontext fix teardown example (#2892)

* doc reqcontext fix teardown example

* remove comments

docs/reqcontext.rst

@@ -193,7 +193,7 @@ contexts until the with block exits.
 
     # teardown functions are called after the context with block exits
 
-    with app.test_client():
+    with app.test_client() as client:
         client.get('/')
         # the contexts are not popped even though the request ended
         print(request.path)
@@ -201,7 +201,6 @@ contexts until the with block exits.
     # the contexts are popped and teardown functions are called after
     # the client with block exists
 
-
 Signals
 ~~~~~~~