Document how to implement feature with RES ecosystem

[mostlyobvious]

Andrzej told me once how he introduced new developer to RES-backed system. It sounded well-thought and started with defining Command, through Command handler, publishing Events and lastly implementing Event handler, all test-driven.

While it may differ from case-to-case, there's definitely some typical flow that could become a habit.

Not strictly RES-related but when @andrzejsliwa told me about It felt like a great idea if adapted to RES tooling. Would love more input as I don't quite remember all details form that story now.

[paneq]

From top down:

• controller creates a command
• a command is passed down to command_bus/application service
• service loads an aggregate and calls a method, stores the events
• aggregate verifies preconditions/rules and generates events
• event(s) are passed to event handlers
• event handlers trigger side-effects (email) and/or build read-models.

[paneq]

@andrzejsliwa was it like that?