fix: correct typo in README regarding tool responses

Author: Jai0401

README.md

@@ -116,7 +116,7 @@ When you call `Runner.run()`, we run a loop until we get a final output.
 2. The LLM returns a response, which may include tool calls.
 3. If the response has a final output (see below for the more on this), we return it and end the loop.
 4. If the response has a handoff, we set the agent to the new agent and go back to step 1.
-5. We process the tool calls (if any) and append the tool responses messsages. Then we go to step 1.
+5. We process the tool calls (if any) and append the tool responses messages. Then we go to step 1.
 
 There is a `max_turns` parameter that you can use to limit the number of times the loop executes.