Update documentation about codehash behaviour according to EIP-1052 and EIP-161

[ustas-eth]

Fixes #14794 by adding a warning for the codehash usage.

[github-actions]

Thank you for your contribution to the Solidity compiler! A team member will follow up shortly.

If you haven't read our contributing guidelines and our review checklist before, please do it now, this makes the reviewing process and accepting your contribution smoother.

If you have any questions or need our help, feel free to post them in the PR or talk to us directly on the #solidity-dev channel on Matrix.

[ustas-eth]

Please, see the following issue: #14794

[r0qs]

Thank you very much @ustas-eth, I just have one comment ;)

[r0qs]

Thanks @ustas-eth. Could you please just squash the commits and rebase with the develop branch? :)

[ustas-eth]

@r0qs I did, but I'm not sure if the result is what you expected. I'm not very proficient with git :')

[r0qs]

@r0qs I did, but I'm not sure if the result is what you expected. I'm not very proficient with git :')

haha no problem, I fixed it for you ;)

Thanks a lot for your contribution!

[r0qs]

I'm kinda of approving myself here, so @cameel, please take a look when you have some time ;)

[mehtavishwa30]

Looks good to me. Approving this! :)