Experiments: multi node logging (#1246)

Cleans up existing "Distributed logging" doc and adds a section on what
and how to use public "Multi node" feature.

Jira ticket: https://wandb.atlassian.net/browse/DOCS-1373

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: ngrayluna