Including Handler in Atmo's concepts

[flaki]

As per my previous Discord comment:

I really miss a 'Handler(s?)' option [from the Atmo→Concepts menu] in part, for completeness' sake, and in part because "state" is a not-too-often-referred to 'concept' as is, whereas handlers are the bread & butter of Atmo. It also happens that the Handler(s) doc would make sense after the Directive, and the state doc talks about handlers, basically, from a 'state' perspective. I wonder if it would make sense to rework it, and name this doc Handlers, explain the "state" as the implementation arising from handlers?

Case in point: in headless mode, there are no handlers and, thus, no "state", per se, either.

As per @ramonh's notes:

Handlers — Should this be covered under Concepts as well? I don’t know why I found myself getting stuck here when reading through.

We should figure out how to improve the exposure and taxonomy of these concepts.

Note: links might be pointing to private Suborbital Team resources and serve as reference, the relevant content have been reproduced in the issue text.

[flaki]

(was accidentally filed in subo initially)

[hola-soy-milk]

Thanks for bringing my note here!

[LauraLangdon]

Closing since this concept will be deprecated soon.