Charter v63: /squad-update tells what a newer release changes, and /squad-upgrade installs it in one step

• /squad-update tells, /squad-upgrade installs (#422, the CEO's decision). /squad-update
  tells what a newer release changes, as /squad-upgrade did, and installs nothing.
  /squad-upgrade installs the latest release, and /squad-upgrade vN a given one, with no
  question, since typing it is the CEO's yes; it need not follow /squad-update. It still brings
  the agents to a safe point first, stops and tells the CEO when a step is left undone or the check
  fails, and asks for the restart and /squad-resume. It ends with the version installed and its
  release's headlines. The squad board's notice of a newer release names /squad-update. §7 says
  so.
• Upgrading from v62: nothing to do by hand. Restart the three sessions, so that each loads the
  new §7 and the board's new notice. This upgrade still runs v62's /squad-upgrade, which asks
  first; from v63 on, it installs without asking.