services: cuirass: Remove 'cuirass-service' procedure.

* gnu/services/cuirass.scm (<cuirass-configuration>)[specifications]:
Remove default value.
(cuirass-service): Remove.
* doc/guix.texi (Continuous Integration): Adjust accordingly.

doc/guix.texi

@@ -12011,21 +12011,16 @@ providing substitutes to others (@pxref{Substitutes}).
 The @code{(gnu services cuirass)} module provides the following service.
-@deffn {Scheme Procedure} cuirass-service @
-       [#:config @code{(cuirass-configuration)}]
-Return a service that runs @command{cuirass}.
-
-The @var{#:config} keyword argument specifies the configuration for
-@command{cuirass}, which must be a @code{<cuirass-configuration>}
-object, by default it doesn't provide any build job.  If you want to
-provide your own configuration you will most likely use the
-@code{cuirass-configuration} special form which returns such objects.
-@end deffn
-In order to add build jobs you will have to set the
-@code{specifications} field.  Here is an example of a cuirass service
-defining a build job based on a specification that can be found in
-Cuirass source tree.
+@defvr {Scheme Procedure} cuirass-service-type
+The type of the Cuirass service.  Its value must be a
+@code{cuirass-configuration} object, as described below.
+@end defvr
+To add build jobs, you have to set the @code{specifications} field of
+the configuration.  Here is an example of a service defining a build job
+based on a specification that can be found in Cuirass source tree.  This
+service polls the Guix repository and builds a subset of the Guix
+packages, as prescribed in the @file{gnu-system.scm} example spec:
 @example
 (let ((spec #~((#:name . "guix")
@@ -12042,11 +12037,12 @@ Cuirass source tree.
                (#:proc . hydra-jobs)
                (#:arguments (subset . "hello"))
                (#:branch . "master"))))
-  (cuirass-service #:config (cuirass-configuration
-                             (specifications #~(list #$spec)))))
+  (service cuirass-service-type
+           (cuirass-configuration
+            (specifications #~(list #$spec)))))
 @end example
-While information related to build jobs are located directly in the
+While information related to build jobs is located directly in the
 specifications, global settings for the @command{cuirass} process are
 accessible in other @code{cuirass-configuration} fields.

gnu/services/cuirass.scm

@@ -30,8 +30,7 @@ (define-module (gnu services cuirass)
             cuirass-configuration
             cuirass-configuration?
 
-            cuirass-service-type
-            cuirass-service))
+            cuirass-service-type))
 
 ;;;; Commentary:
 ;;;
@@ -57,8 +56,8 @@ (define-record-type* <cuirass-configuration>
                     (default 60))
   (database         cuirass-configuration-database ;string (file-name)
                     (default "/var/run/cuirass/cuirass.db"))
-  (specifications   cuirass-configuration-specifications
-                    (default #~'())) ;gexp that evaluates to specification-alist
+  (specifications   cuirass-configuration-specifications)
+                                  ;gexp that evaluates to specification-alist
   (use-substitutes? cuirass-configuration-use-substitutes? ;boolean
                     (default #f))
   (one-shot?        cuirass-configuration-one-shot? ;boolean
@@ -140,6 +139,3 @@ (define cuirass-service-type
      (service-extension shepherd-root-service-type cuirass-shepherd-service)
      (service-extension account-service-type cuirass-account)))))
 
-(define* (cuirass-service #:key (config (cuirass-configuration)))
-  "Return a service that runs cuirass according to CONFIG."
-  (service cuirass-service-type config))