Adding Customer Impact of a CustomersDot outage to runbooks

Zoe Braddockrequested to merge
understanding-customersdb-customer-impact into master

I found it helpful to understand what the customer impact of an outage to just CustomerDot was when scheduling C1 Upgrade CloudSQL Instance for Customers-DB from Postgres 12 to Postgres 16. So I decided to record this information in the runbook for future use as well.

label type::feature

Merge request reports