Documentation: Add note on Azure Support

[dinhhungitsoft]

Beside models from Open AI, now there are the same models such as gpt-3, gpt-3.5 on Azure Open AI services.
I attempt to use those service from Azure but it does not seems to support.
LMQL should support integration with Azure Open AI services.

[lbeurerkellner]

Thanks for raising this. LMQL actually already supports Azure endpoints, see this PR here: #71.

You will need the 'main' version for this, as there was not a release including this yet.

pip install git+https://github.com/eth-sri/lmql

I will keep this issue as a TODO, so we don't forget to update the docs when we release this on pip.