User guide

• Running reports — choosing checks, filtering, where the report goes.
• Snapshots and baselines — recording the state before an upgrade and comparing against it.
• Output formats — text, JSON, YAML, HTML, Markdown, Jira and Confluence, and converting a saved report later.
• Reading the results — what severities, statuses and exit codes mean, and how to act on them.
• Running across a fleet — with Ansible.