Improve examples about usage of runAsyncMain

[PatrickLehnerXI]

Some of the examples don't currently use the runAsyncMain function, while others do. This was a bit confusing at first, and doesn't clearly show how DevCmd is intended to be used.

Note: This feedback was provided internally at XITASO, so I'm creating this issue for tracking.

[PatrickLehnerXI]

DevCmd can be used with or without using the runAsyncMain, but for our common use case, I do think we should recommend using runAsyncMain.

We should maybe add this to our documentation, and we should definitely make our examples consistent.

However: let's also think about how we can keep integration test coverage for commands that don't use runAsyncMain