emacs: Add 'guix-search-by-name'.

* emacs/guix-ui-package.el (guix-search-by-name): New command.
* doc/emacs.texi (Emacs Commands): Document it.

doc/emacs.texi

@@ -163,6 +163,11 @@ Search for packages by a specified regexp.  By default ``name'',
 ``synopsis'' and ``description'' of the packages will be searched.  This
 can be changed by modifying @code{guix-package-search-params} variable.
 
+@item M-x guix-search-by-name
+Search for packages with names matching a specified regexp.  This
+command is the same as @code{guix-search-by-regexp}, except only a
+package ``name'' is searched.
+
 @end table
 
 By default, these commands display each output on a separate line.  If

emacs/guix-ui-package.el

@@ -938,6 +938,17 @@ Interactively with prefix, prompt for PROFILE."
   (guix-package-get-display profile 'regexp regexp
                             (or params guix-package-search-params)))
 
+;;;###autoload
+(defun guix-search-by-name (regexp &optional profile)
+  "Search for Guix packages matching REGEXP in a package name.
+If PROFILE is nil, use `guix-current-profile'.
+Interactively with prefix, prompt for PROFILE."
+  (interactive
+   (list (read-string "Package name by regexp: "
+                      nil 'guix-package-search-history)
+         (guix-ui-read-profile)))
+  (guix-search-by-regexp regexp '(name) profile))
+
 ;;;###autoload
 (defun guix-installed-packages (&optional profile)
   "Display information about installed Guix packages.