Adding lesson on basic proofs

[PetarMax]

Introducing Lesson 22 on basic proofs, using examples from the 0-to-K tutorial

[charala1]

@PetarMax should we name the examples according to the lesson-22-* scheme as in the rest of the tutorial?

[PetarMax]

Yes, please, that naming convention should probably be respected.

[charala1]

Yes, please, that naming convention should probably be respected.

Done. However, I think we should put the whole listings in as opposed to asking the reader to add definitions into the modules (and use lesson-22-{a, b, c...} prefixes for the various files). Maybe this is overkill, I don't know.

[PetarMax]

I'd prefer not to to present the entire file at once, because then I'd have to refer the reader back. Like this, it's all inlined in the text. Alternatively, the lesson itself could be the file, given literate programming. Perhaps that's the way to go?

[Baltoli]

See commands.sh for examples of how the tutorial's literate definitions are compiled in CI. You want each A, B, C module to be individually compilable with the appropriate setting for the main module.