Fix mistake in knowledge base action story example
"utter_greet" is incorrectly listed as an intent in the knowledge base action story.  Replacing with correct intent "query_knowledge_base"
@@ -242,7 +242,7 @@ stories:
steps:
- intent: greet
- action: utter_greet
- - intent: utter_greet
+ - intent: query_knowledge_base
- action: action_query_knowledge_base
- intent: goodbye
- action: utter_goodbye
