docs: update library.mdx (#1406)

Add 's' in the end of keyword "clarification_question"

agent.clarification_question('What is the GDP of the United States?')

docs/library.mdx

@@ -176,7 +176,7 @@ agent.chat('And which one has the most deals?')
 An agent will also be able to ask clarification questions if it does not have enough information to answer the query. For example:
 
 ```python
-agent.clarification_question('What is the GDP of the United States?')
+agent.clarification_questions('What is the GDP of the United States?')
 ```
 
 this will return up to 3 clarification questions that the agent can ask the user to get more information to answer the query.