Increase maintainability

[halbGefressen]

Is your feature request related to a problem? Please describe.
I have recently started to use Plover and like it quite a lot. But it has a few problems, thus I wanted to contribute to fixing them.
But I ran into the problem that the design seems unclear to me. Maybe it's just a skill issue though.

A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]

Describe the solution you'd like

• A short paragraph in the "Contributing" section that explains the structure of the project would probably be beneficial.
• Type annotations help a lot in understanding code that you don't know.
• Maybe someone has another idea...

Describe alternatives you've considered
Not contributing at all... though I really don't wanna do that :)

[user202729]

There's a bit of extra developer docs over in https://plover.readthedocs.io/en/latest/, have you read it?

[halbGefressen]

I am currently reading the API docs, thank you for pointing me there. Couldn't find any conclusive article about the design structure, though, which is why I'm drawing some UML diagrams now (god help me). I'll try to get an overview on the project in the following days and maybe write a small paragraph about the structure. It seems to become a little clearer.