Azure OpenAI Integration - add instructions for working with deployments

[jmatthiesen]

In the documentation for the Azure OpenAI integration it doesn't mention how to specify deployments to use. This is an important detail with Azure OpenAI, because Deployments in the service represent the models that you use. There are a couple ways I know you can specify deployments:

1. In Connection Strings:

"ConnectionStrings": {
  "openAiConnectionName": "Endpoint=https://TODO.openai.azure.com/;Deployment=TODO"
}

2. In AppHost directly:

var openai = builder.AddAzureOpenAI("openai")
    .AddDeployment(
        new(deploymentName, "gpt-4o", "2024-05-13")
    );

There may be some other way as well. I'd appreciate having some more guidance in the docs, since I had to look across a few samples to figure out these options.