Add documentation for all `dev` commands too about lightning

[bitkarrot]

@ecurrencyhodler told me about this issue on stakwork. I am interested. @ShahanaFarooqui

[cdecker]

I wonder if we should really be documenting these. We decided against including the dev- commands in the help output because they are, well, intended for developers. In addition they are commands that are mostly used to manipulate the internals during tests, and do not have a solid interface, i.e., we'd continually be breaking semantic versioning, or we'd have to start building tiny ad-hoc commands to test things in the tests.

These then would also be documented, exposed to users, and users that do not know the intricacies of the dev- commands may end up trying them out and destroying their node.

@rustyrussell what do you think?

[ShahanaFarooqui]

Adding some context from where it started:
Reference issue: Ride-The-Lightning/RTL#1280

A user wanted to forget 3 channels and was unable to execute the command due to missing short_channel_id. Finally, @rustyrussell confirmed that channel_id can also be used. Then he asked to open an issue to add dev documentation with details so that advanced users can refer to the documentation if needed.

However, we can show these commands under advanced category with extra warning, if that helps.

[bitkarrot]

I was just about to ask @ShahanaFarooqui to clarify the task.

Either way I am totally ok what your decision is, to document or not to document. I just got my environment updated and probably won't have time to work on it immediately, so no worries if you guys want to cancel this task. We can also just make a framework and leave it with placeholders if you want.