[translation] [FRENCH] translate the missing "how to" pages

[leaggg]

Hello!

I see that a few translations are missing in French in the "How tos" :

https://gorgonia.org/how-to/troubleshoot-gpu-issues/
https://gorgonia.org/how-to/dot/
https://gorgonia.org/how-to/autodiff/

I could do them if that's ok with you?

Cheers

[owulveryck]

Awesome, thank you