The Website Sign module category is now registered through the core base module data. This is a minor internal organization change that helps keep module categorization consistent and available from the base setup.

Task :  https://www.odoo.com/web?#id=27473&view_type=form&model=project.task&menu_id=4720
Pad : https://pad.odoo.com/p/r.97b6442a45d064bf7753c24f877f083c