Add generic name to .desktop file

This often gives the user more information about what kind of
application this is.
diff --git a/vncviewer/vncviewer.desktop.in.in b/vncviewer/vncviewer.desktop.in.in
index 5abe2fc..d775dde 100644
--- a/vncviewer/vncviewer.desktop.in.in
+++ b/vncviewer/vncviewer.desktop.in.in
@@ -1,5 +1,6 @@
 [Desktop Entry]
 Name=TigerVNC Viewer
+GenericName=Remote Desktop Viewer
 Comment=Connect to VNC server and display remote desktop
 Exec=@BIN_DIR@/vncviewer
 Icon=tigervnc