[gnome-software] Add a description for --version command line option

[Kalev Lember <klember src gnome org>]

commit d04287fd58098e04e74b557fbb97ce1fa0c4af74
Author: Kalev Lember <klember redhat com>
Date:   Thu Nov 26 16:38:33 2015 +0100

    Add a description for --version command line option
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1285831

 src/gs-application.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/src/gs-application.c b/src/gs-application.c
index bd791cd..32766f1 100644
--- a/src/gs-application.c
+++ b/src/gs-application.c
@@ -106,7 +106,8 @@ gs_application_init (GsApplication *application)
                  _("Show profiling information for the service"), NULL },
                { "prefer-local", '\0', 0, G_OPTION_ARG_NONE, NULL,
                  _("Prefer local file sources to AppStream"), NULL },
-               { "version", 0, 0, G_OPTION_ARG_NONE, NULL, NULL, NULL },
+               { "version", 0, 0, G_OPTION_ARG_NONE, NULL,
+                 _("Show version number"), NULL },
                { NULL }
        };