Fix Cart-Pole Render Angle

[Kinvert]

When rendering Cart Pole, the pole is at the wrong angle. This one liner fixes it.

I saw you want issues created. I didn't see how to do it here so I followed the link you provided in your README.md and it went to another repo. I created the issue here: tensorflow/tfjs#8538

My son and I noticed it when I was trying your demo. I dug through the code and found this, and the sign swap works.

[google-cla]

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[Kinvert]

For some reason your CLA thing is tying to other accounts instead of my GitHub account. I tried opening in a private window and it wants me to sign in with my Google account. That has a different email address. How do I sign this CLA without mixing up email addresses?