Man pages matching name probe::signal.sys_tgkill in section 3stap:

probe::signal.sys_tgkill.3stap.en	debian 10 / systemtap-doc
probe::signal.sys_tgkill.3stap.en	debian 11 / systemtap-doc
probe::signal.sys_tgkill.3stap.en	debian 12 / systemtap-doc