New sysadmin lecture

A brief onboarding guide for new production sysadmins covering core responsibilities: respecting user privacy, thinking before acting, practicing changes locally, running SQL queries in transactions, and avoiding irreversible actions. Also covers spear phishing awareness, explaining how bad actors may impersonate colleagues or users to exploit admin access, and advising verification steps like NickServ identification, DKIM-signed emails, and PGP challenges.