[3.2.x] Fixed docs header underlines in security archive.
[3.2.x] Fixed docs header underlines in security archive.

Backport of d9cee3f5f2f90938d2c2c0230be40c7d50aef53d from main

wkschwartz/django,wkschwartz/django,koordinates/django,koordinates/django,koordinates/django,wkschwartz/django,wkschwartz/django,koordinates/django