services: base: Deprecate 'login-service' procedure.

* doc/guix.texi (Base Services): Replace with login-service-type.
* gnu/services/base.scm (login-service): Deprecate procedure.
* gnu/system/install.scm (%installation-services): Use login-service-type.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

doc/guix.texi

@@ -18101,14 +18101,14 @@ Return a new record for the host at @var{address} with the given
 host names.
 @end defun
 
-@deffn {Scheme Procedure} login-service @var{config}
-Return a service to run login according to @var{config}, a
-@code{<login-configuration>} object, which specifies the message of the day,
-among other things.
-@end deffn
+@defvar login-service-type
+Type of the service that provides a console login service, whose value
+is a @code{<login-configuration>} object.
+@end defvar
 
 @deftp {Data Type} login-configuration
-This is the data type representing the configuration of login.
+Data type representing the configuration of login, which specifies the
+@acronym{MOTD, message of the day}, among other things.
 
 @table @asis
 

gnu/services/base.scm

@@ -158,7 +158,7 @@ (define-module (gnu services base)
             login-configuration
             login-configuration?
             login-service-type
-            login-service
+            login-service  ; deprecated
 
             agetty-configuration
             agetty-configuration?
@@ -937,7 +937,8 @@ (define login-service-type
                  "Provide a console log-in service as specified by its
 configuration value, a @code{login-configuration} object.")))
 
-(define* (login-service #:optional (config (login-configuration)))
+(define-deprecated (login-service #:optional (config (login-configuration)))
+  login-service-type
   "Return a service configure login according to @var{config}, which specifies
 the message of the day, among other things."
   (service login-service-type config))

gnu/system/install.scm

@@ -347,8 +347,9 @@ (define bare-bones-os
                      (virtual-terminal "tty1")
                      (login-program (installer-program))))
 
-           (login-service (login-configuration
-                           (motd motd)))
+           (service login-service-type
+                    (login-configuration
+                     (motd motd)))
 
            ;; Documentation.  The manual is in UTF-8, but
            ;; 'console-font-service' sets up Unicode support and loads a font