Rename AZUREAI_OPENAI_BASE_URL to AZUREAI_BASE_URL in Docs

[lon-tierney]

Code seems to expect a different environment variable.

This PR contains:

• New features
• Changes to dev-tools e.g. CI config / github tooling
• Docs
• Bug fixes
• Code refactor

What is the current behavior? (You can also link to an open issue here)

Execution complains that AZUREAI_BASE_URL environment variable is missing. Changing AZUREAI_OPENAI_BASE_URL to AZUREAI_BASE_URL resolves issues.

What is the new behavior?

Correct docs to match codebase expectation

Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)

No

Other information:

[jjallaire]

I think the real fix here is to make that environment variable work properly. Note that we already have AZUREAI_MISTRAL_BASE_URL and AZUREAI_ANTHROPIC_BASE_URL so we want both (a) Consistency in how environment variables are formed; and (b) The ability to have separate environment variables per model provider (as a generic AZUREAI_BASE_URL wouldn't work if you were using multiple model providers on Azure).

Let me take a look and see whether there is an easy fix for the error you are seeing.

[jjallaire]

Yes, AZUREAI_BASE_URL is actually reserved for when you are using the azureai/ provider rather than the OpenAI provider.

It might be good if you could just provide a snippet of get_model() code that demonstrates the scenario where you are seeing this error and we can take it from there.