[UPDATE] An error in quiz 2

[S-N-O-R-L-A-X]

What do you want to improve?

• Explain the typo/error or the part of the course you want to improve

• Also, don't hesitate to open a Pull Request with the update.

In second quiz, there is such a problem.

However, the third option is the definition of Q-function instead of Q-learning.

So it should not be included as the answer.

[S-N-O-R-L-A-X]

I have raised a PR for this. https://github.com/huggingface/deep-rl-class/pull/493

[simoninithomas]

Thanks 🤗 I merged the PR. I'm closing the issue