services: cuirass: Add a substitute-urls argument.

* gnu/services/cuirass.scm (<cuirass-remote-worker-configuration>): Add a
substitute-urls field.
(cuirass-remote-worker-shepherd-service): Honor it.
* doc/guix.texi (Cuirass remote building): Document it.

1 files changed, 3 insertions, 0 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index ac6c11949f5..78c1c09858b 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -27928,6 +27928,9 @@ Location of the log file.
 @item @code{publish-port} (default: @code{5558})
 The TCP port of the publish server.  It defaults to @code{5558}.
 
+@item @code{substitute-urls} (default: @code{%default-substitute-urls})
+The list of URLs where to look for substitutes by default.
+
 @item @code{public-key}
 @item @code{private-key}
 Use the specific @var{file}s as the public/private key pair used to sign