Man pages matching name gnutls_srp_set_server_credentials_function in section 3:

gnutls_srp_set_server_credentials_function.3.en	debian 10 / gnutls-doc
gnutls_srp_set_server_credentials_function.3.en	debian 11 / gnutls-doc
gnutls_srp_set_server_credentials_function.3.en	debian 12 / gnutls-doc