guide: Sharing Experiments

[dberenbaum]

The utility of dvc exp push and dvc exp pull isn't all that clear now. It would be great to develop a typical scenario to show how sharing experiments is useful.

Ideas:

• If several experiments have similar metric values and I want to share with my team before deciding which experiment to choose.
• If I need to keep a record of alternative experiments that I tried to document/audit my model development process.

Extracted from #2269.

[jorgeorpinel]

I'd go for a guide on this (there are some exp-related use case ideas in #2270 (comment) though).

I think we'll want to make https://dvc.org/doc/user-guide/experiment-management a section and have sub-pages. This can be one of them.