[gdm] build: fix help string for --with-group

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 1f035fbd533eaf0c42ccc09b8a11fe21cdad5755
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Sat Jan 9 23:28:50 2016 -0600

    build: fix help string for --with-group
    
    Another great contribution to free software. ;)
    
    https://bugzilla.gnome.org/show_bug.cgi?id=760389

 configure.ac |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 5496f27..d966f9a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -454,8 +454,8 @@ dnl ---------------------------------------------------------------------------
 
 withval=""
 AC_ARG_WITH(group,
-            AS_HELP_STRING([--with-group=<username>],
-                           [specify gdm's user name]))
+            AS_HELP_STRING([--with-group=<group>],
+                           [specify gdm's group name]))
 
 if test x$withval != x; then
        GDM_GROUPNAME="$withval"