Fix test queue reset! documentation

I ran into this with version 2.4.0, not sure if this is a just a typo or if the interface changed between versions.

README.md

@@ -150,7 +150,7 @@ client.test_queue.identify # => []
 client.test_queue.page # => []
 client.test_queue.screen # => []
 
-client.reset!
+client.test_queue.reset!
 
 client.test_queue.all # => []
 ```