The documentation that should survive staff turnover

Start with tenants, domains, critical applications, vendors, system owners, support contacts, and the architecture connecting them. Keep a clear record of where administrative access is managed without placing secrets in general documentation.

Document onboarding, offboarding, device standards, incident escalation, backup and recovery, and the decisions behind major configurations.

Assign an owner and review date to each important document. A usable, maintained set of runbooks is more valuable than a large collection of outdated instructions.