demote Sourcegraph.com docs, Sourcegraph Cloud refers to managed instances
Created by: sqs
- Removed most docs from Sourcegraph.com about private code. I kept docs that were about managing an existing account and removed docs that were about usage or getting started.
- Sourcegraph Cloud now always refers to managed instances across our docs.
- Did not set up redirects because we will soon reuse
/cloud
to mean managed instances.
Test plan
None (docs only).