High level description of stacker.news codebase

[SouthKoreaLN]

Is your feature request related to a problem? Please describe.

Just wondering if some other new contributors to Stacker.news would like to have a high-level introduction of how everything fits together in the stacker.news codebase. I am truly new to all of this, not just stacker.news, so it could be that this would not benefit anyone else but me. In such case, it is of course not worth the trouble to draft something. And I am for sure just learning by doing, constantly grepping to find the places where things are defined and implemented, called and stored, etc.

Describe the solution you'd like

Add an md file in the docs folder that describes the structure, the high-level logic linking the different parts, the philosophy behind certain choices (stateless, etc), some preferred practices, etc.
This could then be loaded of course in the FOSS homepage (see #1058).

Describe alternatives you've considered

The alternative is nearly as good, i.e. just learning by doing.

Additional context

Please don't waste time on this if I am the only one that would benefit from this.