Code examples on how to use Rust SDK with each supported building block

[greenie-msft]

Consider adding examples in the Github repo (maybe as a README?) on how to use the Rust SDK for each of the supported Building Blocks, e.g how to use the Rust SDK for Service Invocation.

These examples will provide clarity on how to use the SDK. Additionally, we can raise visibility into the SDK by linking to the examples from each Building Block overview page.