Fix updates and upgrades in distributed cloud guide
Review of the Distributed Cloud Guide to adjust to USM
Fix merge conflict https://review.opendev.org/c/starlingx/docs/+/937086
Fix merge conflict with https://review.opendev.org/c/starlingx/docs/+/937352
Created Horizon Section for Orchestrate Subcloud Prestage
Change-Id: I8b288e35ec76fcbc11ccbe7715aefff70722094d
Signed-off-by: Elisamara Aoki Gonçalves <elisamaraaoki.goncalves@windriver.com>