Add more logging messages

[kneasle]

Ideally, we'd have log::trace! in every function, and log::debug! when debug output might be useful.

[micouy]

Are you talking about literally every function in the whole crate? I find your project very interesting so I could get to know the project better through this task. Do you have any other advice on how to begin contributing? I've already read ARCHITECTURE.md.

[kneasle]

Ok maybe not every function 😅 - I think I was having some trouble debugging something when I made this issue.

To be honest, the point of this is more to encourage new contributors to look round the code (as you noticed) - IMO the place where logging is needed most is the code that handles editing (which currently resides in sapling::editor::Editor).

There currently isn't much contributor advice other than CONTRIBUTING.md/ARCHITECTURE.md and to just get stuck into something 😁. However, if there is anything that would be useful but doesn't currently exist then please let me know or make a PR for it.