emacs: Add 'M-x guix-installed-{user/system}-packages'.

* emacs/guix-ui-package.el (guix-installed-user-packages)
(guix-installed-system-packages): New commands.
* doc/emacs.texi (Emacs Commands): Document them.

doc/emacs.texi

@@ -150,7 +150,13 @@ Commands for displaying packages:
 Display all/newest available packages.
 
 @item M-x guix-installed-packages
-Display all installed packages.
+@itemx M-x guix-installed-user-packages
+@itemx M-x guix-installed-system-packages
+Display installed packages.  As described above, @kbd{M-x
+guix-installed-packages} uses an arbitrary profile that you can specify,
+while the other commands display packages installed in 2 special
+profiles: @file{~/.guix-profile} and @file{/run/current-system/profile}
+(only on GuixSD).
 
 @item M-x guix-obsolete-packages
 Display obsolete packages (the packages that are installed in a profile

emacs/guix-ui-package.el

@@ -981,6 +981,19 @@ Interactively with prefix, prompt for PROFILE."
   (interactive (list (guix-ui-read-profile)))
   (guix-package-get-display profile 'installed))
 
+;;;###autoload
+(defun guix-installed-user-packages ()
+  "Display information about Guix packages installed in a user profile."
+  (interactive)
+  (guix-installed-packages guix-user-profile))
+
+;;;###autoload
+(defun guix-installed-system-packages ()
+  "Display information about Guix packages installed in a system profile."
+  (interactive)
+  (guix-installed-packages
+   (guix-packages-profile guix-system-profile nil t)))
+
 ;;;###autoload
 (defun guix-obsolete-packages (&optional profile)
   "Display information about obsolete Guix packages.