fixbug: use a share context to pass the repo path information

examples/use_off_the_shelf_agent.py

@@ -5,13 +5,15 @@ Author: garylin2099
 """
 import asyncio
 
+from metagpt.context import Context
 from metagpt.logs import logger
 from metagpt.roles.product_manager import ProductManager
 
 
 async def main():
     msg = "Write a PRD for a snake game"
-    role = ProductManager()
+    context = Context()  # Used to share repo path information between multiple actions within the role.
+    role = ProductManager(context=context)
     result = await role.run(msg)
     logger.info(result.content[:100])