Where can I find the ca-certificates.crt file from the nss-certs package?

[Reza Housseini]

Hello Guix

For an application I need a ca-certificates.crt file and according to 
[1] I can get it from the package nss-certs, but

ls $(guix build nss-certs) | grep ca-certificates.crt
does not list any certificates, what am I doing wrong?

Best,
Reza

[1] https://guix.gnu.org/en/manual/devel/en/guix.html#X_002e509-Certificates