guide: all the ways to use checkpoints

[dberenbaum]

As shown in https://github.com/iterative/dvc-checkpoints-mnist under "Switch between scenarios," there are multiple different ways to integrate checkpoints into a project:

• Using dvclive
• Using make_checkpoint
• Using a manually created signal file
• Only including checkpoints: true in dvc.yaml without any in-code checkpoints (but this seems like an unlikely scenario that might be unnecessary or useful just to show the basics of how checkpoints work - see Document checkpoints without make_checkpoint() #2292)

There is already a link in https://dvc.org/doc/user-guide/experiment-management to that example repo. Is this sufficient for now? Should the user guide provide more explanation rather than leave it in the readme of the example repo?

[jorgeorpinel]

There is already a link in https://dvc.org/doc/user-guide/experiment-management to that example repo. Is this sufficient for now?

And soon #2373

I think it's sufficient for now. But ideally we should have an Experiments guide sub section with better separated pages (each shorter but covering more things as a whole), IMO.

p.s. basically #2269

[jorgeorpinel]

Should we merge this issue with #2769?

[iesahin]

It looks #2769 itself is becoming too big to manage. In this issue, the goal was to demonstrate how to use (1) DVCLive, (2) Python API (make_checkpoint) and (3) Signal File. These three ways need a dedicated checkpoints guide.