csf PT_USERKILL Recommendation

We wanted to reiterate the points made in the csf configuration and during csf restart regarding the PT_USERKILL option and the problems it can cause on servers as there appears to have been a spate of people enabling the option, which we do not recommend for stability reasons.

As csf itself now reports:

*WARNING* PT_USERKILL should not normally be enabled as it can easily 
lead to legitimate processes being terminated, use csf.pignore instead

And as stated in /etc/csf/csf.conf:

# Warning: We don't recommend enabling this option unless absolutely necessary
# as it can cause unexpected problems when processes are suddenly terminated.
# It can also lead to system processes being terminated which could cause
# stability issues. It is much better to leave this option disabled and to
# investigate each case as it is reported when the triggers above are breached