Product design handbook: missing reference docs are bugs (#22541)

This + announcement addresses of the following Fleet objective
([OKRs](https://docs.google.com/spreadsheets/d/1Hso0LxqwrRVINCyW_n436bNHmoqhoLhC8bcbvLPOs9A/edit?gid=1846478041#gid=1846478041)):

Handbook and train team that anytime there is a missing or incorrect
config setting or REST API in the docs, it is a released bug to be filed
and fixed ASAP.

handbook/product-design/README.md

@@ -137,6 +137,8 @@ Next, the API design DRI reviews all user stories and bugs with the release mile
 
 To signal that the reference docs branch is ready for release, the API design DRI opens a PR to `main`, adds the DRI for what goes in a release as the reviewer, and adds the release milestone.
 
+> Anytime there is a missing or incorrect configuration option or REST API endpoint in the docs, it is treated as a released bug to be filed and fixed ASAP.
+
 ### Interview a Product Designer candidate
 
 Ensure the interview process follows these steps in order. This process must follow [creating a new position](https://fleetdm.com/handbook/company/leadership#creating-a-new-position) through [receiving job applications](https://fleetdm.com/handbook/company/leadership#receiving-job-applications).