[glabels] Add a missing tag to the AppData file

[Richard Hughes <rhughes src gnome org>]

commit 8fee4e4713a5af9e2025bad0f024647e5e9693f8
Author: Richard Hughes <richard hughsie com>
Date:   Mon Jan 25 13:31:31 2016 +0000

    Add a missing tag to the AppData file

 data/appdata/glabels-3.appdata.xml.in |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/data/appdata/glabels-3.appdata.xml.in b/data/appdata/glabels-3.appdata.xml.in
index 61ec1d5..7fc99fd 100644
--- a/data/appdata/glabels-3.appdata.xml.in
+++ b/data/appdata/glabels-3.appdata.xml.in
@@ -24,4 +24,5 @@
   </screenshots>
   <url type="homepage">http://glabels.org/</url>
   <updatecontact>evins_at_snaught.com</updatecontact>
+  <project_group>GNOME</project_group>
 </application>