Update tools.md (#212)

Instructions to check if your model supports functions is incorrect, it
is missing a `?` on the method name.

Author: seemiller

docs/guides/tools.md

@@ -130,7 +130,7 @@ puts response.content
 ```
 
 {: .warning }
-Ensure the model you select supports function calling/tools. Check model capabilities using `RubyLLM.models.find('your-model-id').supports_functions`. Attempting to use `with_tool` on an unsupported model will raise `RubyLLM::UnsupportedFunctionsError`.
+Ensure the model you select supports function calling/tools. Check model capabilities using `RubyLLM.models.find('your-model-id').supports_functions?`. Attempting to use `with_tool` on an unsupported model will raise `RubyLLM::UnsupportedFunctionsError`.
 
 ## The Tool Execution Flow
 
@@ -210,4 +210,4 @@ Treat any arguments passed to your `execute` method as potentially untrusted use
 *   [Chatting with AI Models]({% link guides/chat.md %})
 *   [Streaming Responses]({% link guides/streaming.md %}) (See how tools interact with streaming)
 *   [Rails Integration]({% link guides/rails.md %}) (Persisting tool calls and results)
-*   [Error Handling]({% link guides/error-handling.md %})
+*   [Error Handling]({% link guides/error-handling.md %})