Add Lukasz Wasikowski to contributors for security/rkhunter

He is also maintainer of these ports:
mail/sgwi
sysutils/apachetop
sysutils/modman
www/mod_macro22
www/mod_mpm_itk

PR: 220765
Approved by: garga (mentor)
Differential Revision: https://reviews.freebsd.org/D11613