docs: duplicate -q --json call in example cli reference

What is the type of issue?

_No response_

What is the issue?

the example uses both -q and --json which are contradictory flags, (the implementation it's also broken, but that's another thing)

https://github.com/openai/codex/pull/736

Where did you find it?

its on the main README.md https://github.com/openai/codex/blob/main/README.md