Document the procedure to restart a k8s deployment

Summary

During production#6182 (closed) we needed to restart the pods of the web fleet. @skarbek assisted and ran a series of commands to accomplish this task without downtime.

We should have a runbook for this, which outlines those steps.

Related Incident(s)

Originating issue(s): production#6182 (closed)

Desired Outcome/Acceptance criteria

We should have a runbook for this, which outlines those steps.

Associated Services

Corrective Action Issue Checklist

• link the incident(s) this corrective action arose out of
• give context for what problem this corrective action is trying to prevent from re-occurring
• assign a severity label (this is the highest sev of related incidents, defaults to 'severity::4')
• assign a priority (this will default to 'priority::4')