gnome3.gspell: complete meta attribute

pkgs/desktops/gnome-3/misc/gspell/default.nix

···
   buildInputs = [ glib gtk3 isocodes ];
 
   meta = with stdenv.lib; {
+    description = "A spell-checking library for GTK+ applications";
+    homepage = https://wiki.gnome.org/Projects/gspell;
+    license = licenses.lgpl21Plus;
+    maintainers = gnome3.maintainers;
     platforms = platforms.linux;
   };
 }