Add a section to the end of the https://github.com/dotnet/docs/blob/main/docs/ai/quickstarts/text-to-image.md article that shows how to use this stuff with hosting, by using things like AddAzureOpenAIClient and AddImageGenerator (similar to https://github.com/ericstj/imageGeneratorSample/blob/8a976997f5a762885c2fa3e76c206723263c3ded/imageGeneratorSample.Web/Program.cs#L16-L26.)

Originally posted by @ericstj in #49391 (comment)

Associated WorkItem - 508903