[Website]: Add troubleshooting section about failed check-ins and 401 #3708
Description
Type of issue
None
What documentation page is affected
https://www.elastic.co/docs/troubleshoot/ingest/fleet/common-problems
What happened?
We should cover the situation that if an Elastic Agent in versions < 9.1.0 or 8.19.0 gets a 401 while checkin in for more than 7 times, it gets auto-unenrolled.
This behavior has been changed on 9.1.0 and 8.19.0, removing the auto-unenrollment.
Additional info
No response