Fixed Typo in Question Graph Sub Command (#702)

Author: izzyacademy

examples/pydantic_ai_examples/question_graph.py

@@ -173,7 +173,7 @@ async def run_as_cli(answer: str | None):
     except (IndexError, AssertionError):
         print(
             'Usage:\n'
-            '  uv run -m pydantic_ai_examples.question_graph meriad\n'
+            '  uv run -m pydantic_ai_examples.question_graph mermaid\n'
             'or:\n'
             '  uv run -m pydantic_ai_examples.question_graph continuous\n'
             'or:\n'