Docs - Update Praefect docs with multiple virtual storages
What does this MR do?
Bring Praefect docs up to date with the multiple virtual storage nodes configuration change.
Also combine the praefect example config into a single entry, this was only split it two due to conflicting MRs.
Closes gitaly#2258 (closed)
Edited by 🤖 GitLab Bot 🤖