linux desktop icon update (merge from devbr6)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@46427 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/icons/grass.desktop

@@ -2,8 +2,8 @@
 Type=Application
 Encoding=UTF-8
 Name=GRASS GIS
-Comment=
-Categories=Application;Education;Geography;
+Comment=Geographic Information System
+Categories=Education;Science;Geoscience;Geography;
 Exec=grass7
 Icon=/usr/share/icons/grass-48x48.png
 Terminal=true