Update function call doc with example of not using decorator syntax. (m…

…icrosoft#1441)

* update function call doc to address microsoft#1213

* typo

website/docs/Use-Cases/agent_chat.md

@@ -149,6 +149,19 @@ You can check the JSON schema generated by the decorator `chatbot.llm_config["to
      'description': 'Quote currency'}},
    'required': ['base_amount']}}}]
 ```
+
+Python decorators are functions themselves. If you do not want to use the
+`@chatbot.register...` decorator syntax,
+you can call the decorators as functions:
+
+```python
+# Register the function with the chatbot's llm_config.
+chatbot.register_for_llm(description="Currency exchange calculator.")(currency_calculator)
+
+# Register the function with the user_proxy's function_map.
+user_proxy.register_for_execution()(currency_calculator)
+```
+
 4. Agents can now use the function as follows:
 ```python
 user_proxy.initiate_chat(