[file-roller] Add a missing tag to the AppData file

[Richard Hughes <rhughes src gnome org>]

commit c7963b5ebdfa74e07a792fc08493eb6a1ab3cefb
Author: Richard Hughes <richard hughsie com>
Date:   Mon Jan 25 13:12:07 2016 +0000

    Add a missing tag to the AppData file

 data/org.gnome.FileRoller.appdata.xml.in |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/data/org.gnome.FileRoller.appdata.xml.in b/data/org.gnome.FileRoller.appdata.xml.in
index e031e7c..8a18c16 100644
--- a/data/org.gnome.FileRoller.appdata.xml.in
+++ b/data/org.gnome.FileRoller.appdata.xml.in
@@ -33,4 +33,5 @@
     <kudo>Notifications</kudo>
     <kudo>UserDocs</kudo>
   </kudos>
+  <project_group>GNOME</project_group>
 </application>