[bug#46031] services: cuirass: Add "simple-cuirass-services".

[Mathieu Othacehe]

Hello Jonathan,

> Is it intended that I need to import `(guix channels)`? Shouldn't that
> come with the cuirass service module?

Yes you need it to declare the channels that are passed in the
"channels" field of "simple-cuirass-configuration". Maybe I should add a
comment about it in the documentation.

Thanks,

Mathieu