After installation of FAQ module you can see new groups - faq & faq_approval. Give for agents rights in this groups (or only in faq) and yiu will see this menu items in main menu.
Best regards Yuri Kolesnikov
OTRS 5.0.14, ITSM 5.0.14
SUSE 13.2, MariaDB 10.0.22(productive)
OTRS 5.0.14, ITSM 5.0.14(test)