Add diagram to readme

[craigomatic]

Motivation and Context

To make it easier for a developer to understand how the Azure Function integrates the Semantic Kernel.

Description

This PR adds a single image to the readme for the Azure Function that shows the basic flow of data from the caller via HTTP POST, to the Azure Function/Semantic Kernel, which in turn makes a HTTP POST request to Azure Open AI/Open AI

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows SK Contribution Guidelines (https://github.com/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
• The code follows the .NET coding conventions (https://learn.microsoft.com/dotnet/csharp/fundamentals/coding-style/coding-conventions) verified with dotnet format
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

[dluc]

• the numbers in yellow are extremely hard to read
• we should rename "inputs" to "variables" to be consistent with SK terminology
• I would remove the OpenAI logo, use an image that is good both for OpenAI and Azure OpenAI

Clearning to address dluc's feedback

[craigomatic]

• the numbers in yellow are extremely hard to read

Ruokan is helping to fix

• we should rename "inputs" to "variables" to be consistent with SK terminology

The samples use a slightly different model, if we rename here we would also want to rename the models used by both the client and azure function samples.

• I would remove the OpenAI logo, use an image that is good both for OpenAI and Azure OpenAI

There doesn't really seem to be a specific logo that Azure OpenAI uses to differentiate from OpenAI, seems to be the same logo in both places:
https://azure.microsoft.com/en-us/products/cognitive-services/openai-service/

https://openai.com/

Any suggestions on a more generic logo?

[alexchaomander]

• the numbers in yellow are extremely hard to read

Ruokan is helping to fix

• we should rename "inputs" to "variables" to be consistent with SK terminology

The samples use a slightly different model, if we rename here we would also want to rename the models used by both the client and azure function samples.

• I would remove the OpenAI logo, use an image that is good both for OpenAI and Azure OpenAI

There doesn't really seem to be a specific logo that Azure OpenAI uses to differentiate from OpenAI, seems to be the same logo in both places: https://azure.microsoft.com/en-us/products/cognitive-services/openai-service/

https://openai.com/

Any suggestions on a more generic logo?

Maybe just put them side by side? Eventually we may update the image with other model providers like Cohere, Anthropic etc?