Configuring virt-who for VM subscriptions, troubleshooting sections.

• Fix "virt-who troubleshooting methods". Separate multiple commands in code blocks - one command per step. Maybe break into separate modules if this seems useful.
• Review Snibox snippets and add them, if appropriate.
• Ensure that the Sat guide does not duplicate troubleshooting steps in RHEL Getting Started with System Registration in Subscription Central.