Ensure shell commands in docs are correct and outputs are valid

[cptartur]

Which components does the task require to be changed? (think hard pls)

snforge, sncast

Description

Right now, we do not have any mechanism for validating if shell commands (e.g. calls to snforge test etc) in docs are up to date and correct. We should ensure that any command that user can copy from the documentation works and behaves as described.

An minimal solution would be ensuring that the commands are in fact runnable and execute correctly.

Later (feel free to create a separate task for that after minimal is implemented), we should introduce a mechanism to validate if outputs included in the documentation match these produced by the real program.