guide: document config options (-c)

[jorgeorpinel]

-c is being used as a catch-all and a way to avoid specifying the actual expected options for each command

The reason to use -c instead of --<option name> is because different implementations have different set of options. and adding options dynamically will probably require a lot of our cli framework butchering. we might do it later...

From documentation point of view, we need a dedicated page for each implementation (not only target envs, but other base classes too). It's huge amount of work but it needs to be done at some point

Originally posted by @mike0sv in iterative/mlem#233 (comment)

[aguschin]

outdated, since we removed those in 0.3.0