Fix the link to the launch script tutorial in README.md
Fix the link to the launch script tutorial in README.md

PiperOrigin-RevId: 400434620
Change-Id: I41b03b6a5bb97c6176624ba7c6a19e74cea2436a
GitOrigin-RevId: 5ef48f5cc9b12dc120ad61c6011e1bd8453b147b

deepmind/xmanager,deepmind/xmanager