move docs/resources/Walkthrough/*.png under images sub-folder

[joshfree]

There are a number of images checked in under https://github.com/microsoft/mcp/tree/main/servers/Azure.Mcp.Server/docs/resources/Walkthrough that are referenced from the VS Code VSIX README.md. These binary files should move under the existing https://github.com/microsoft/mcp/tree/main/servers/Azure.Mcp.Server/images folder. "walkthrough" should have a better name to make it clearer that these are used by the VS Code VSIX.