Man pages matching name ipsec.secrets in section 5:

ipsec.secrets.5.en	debian 10 / libreswan
ipsec.secrets.5.en	debian 10 / strongswan-starter
ipsec.secrets.5.en	debian 11 / libreswan
ipsec.secrets.5.en	debian 11 / strongswan-starter
ipsec.secrets.5.en	debian 12 / libreswan
ipsec.secrets.5.en	debian 12 / strongswan-starter