Improve language around

features/configuring_responses/mixed_responses.feature

@@ -1,9 +1,12 @@
 Feature: Mixed responses
 
-  Use `and_invoke` to invoke a Proc when a message is received. Pass `and_invoke` multiple
-  Procs to have different behavior for consecutive calls. The final Proc will continue to be
+  Use `and_invoke` to invoke a callable when a message is received. Pass `and_invoke` multiple
+  callables to have different behavior for consecutive calls. The final callable will continue to be
   called if the message is received additional times.
 
+  Note: The invoked callable will be invoked with any arguments, so it is recommended to use a `lambda`
+  or similar with the same arity as your method but you can use a `proc` if you do not care (e.g. when raising).
+
   Scenario: Mixed responses
     Given a file named "raises_and_then_returns.rb" with:
       """ruby