doc: Add desktop configuration example.

* gnu/system/examples/bare-bones.tmpl: Change 'packages' and
  'host-name'.  Remove D-Bus, Avahi, and SLiM services, and add lsh
  instead.
* gnu/system/examples/desktop.tmpl: New file.
* Makefile.am (EXAMPLES): Add it.

Makefile.am

@@ -135,7 +135,8 @@ KCONFIGS =					\
 
 # Templates, examples.
 EXAMPLES =					\
-  gnu/system/examples/bare-bones.tmpl
+  gnu/system/examples/bare-bones.tmpl		\
+  gnu/system/examples/desktop.tmpl
 
 GOBJECTS = $(MODULES:%.scm=%.go) guix/config.go guix/tests.go
 

gnu/system/examples/bare-bones.tmpl

@@ -1,12 +1,13 @@
-;; This is an operating system configuration template.
+;; This is an operating system configuration template
+;; for a "bare bones" setup, with no X11 display server.
 
 (use-modules (gnu))
-(use-service-modules xorg networking dbus avahi)
-(use-package-modules xorg avahi)
+(use-service-modules networking ssh)
+(use-package-modules admin)
 
 (operating-system
-  (host-name "antelope")
-  (timezone "Europe/Paris")
+  (host-name "komputilo")
+  (timezone "Europe/Berlin")
   (locale "en_US.UTF-8")
 
   ;; Assuming /dev/sdX is the target hard disk, and "root" is
@@ -36,12 +37,10 @@
                 (home-directory "/home/alice"))))
 
   ;; Globally-installed packages.
-  (packages (cons xterm %base-packages))
+  (packages (cons tcpdump %base-packages))
 
-  ;; Add services to the baseline: the SLiM log-in manager
-  ;; for Xorg sessions, a DHCP client, Avahi, and D-Bus.
-  (services (cons* (slim-service)
-                   (dhcp-client-service)
-                   (avahi-service)
-                   (dbus-service (list avahi))
+  ;; Add services to the baseline: a DHCP client and
+  ;; an SSH server.
+  (services (cons* (dhcp-client-service)
+                   (lsh-service #:port-number 2222)
                    %base-services)))

gnu/system/examples/desktop.tmpl

@@ -0,0 +1,42 @@
+;; This is an operating system configuration template
+;; for a "desktop" setup with X11.
+
+(use-modules (gnu) (gnu system nss))
+(use-service-modules desktop)
+(use-package-modules xfce ratpoison wicd avahi xorg)
+
+(operating-system
+  (host-name "antelope")
+  (timezone "Europe/Paris")
+  (locale "en_US.UTF-8")
+
+  ;; Assuming /dev/sdX is the target hard disk, and "root" is
+  ;; the label of the target root file system.
+  (bootloader (grub-configuration (device "/dev/sdX")))
+  (file-systems (cons (file-system
+                        (device "root")
+                        (title 'label)
+                        (mount-point "/")
+                        (type "ext4"))
+                      %base-file-systems))
+
+  (users (list (user-account
+                (name "bob")
+                (comment "Alice's brother")
+                (group "users")
+                (supplementary-groups '("wheel"
+                                        "audio" "video"))
+                (home-directory "/home/bob"))))
+
+  ;; Add Xfce and Ratpoison; that allows us to choose
+  ;; sessions using either of these at the log-in screen.
+  (packages (cons* xfce ratpoison    ;desktop environments
+                   xterm wicd avahi  ;useful tools
+                   %base-packages))
+
+  ;; Use the "desktop" services, which include the X11
+  ;; log-in service, networking with Wicd, and more.
+  (services %desktop-services)
+
+  ;; Allow resolution of '.local' host names with mDNS.
+  (name-service-switch %mdns-host-lookup-nss))