Forgot to add: please include a GNU/Guix-style commit message 
like:

    gnu: Add strongswan service.

    * gnu/services/vpn.scm (strongswan-configuration): New record 
    type.
    (charon-plugins, strongswan-configuration-file)
    (strongswan-shepherd-service, strongswan-service-type): New 
    variables.
    * doc/guix.tex (VPN Services): Document them all!

Kind regards,

T G-R