Validation Filter documentation is gone

[kevin-j-morse]

Sometime after September 25, the documentation page for Validation Filters https://www.php.net/manual/en/filter.filters.validate.php has disappeared as well as the link to this documentation on the Types of filters page https://www.php.net/manual/en/filter.filters.php

[Girgias]

Yes, this is an intended change from #3941

The whole objective is to move all the sanitization filters into the constant page aswell, as it was outdated, had rendering issues (and still has) and a bunch of other issues.