GD removed (#133) - updated glossary

Author: havatv

en/glossary.txt

@@ -45,8 +45,12 @@
     GD
         `GD <http://www.libgd.org/Main_Page>`__ is a graphics library for 
         dynamic generation of images.  It was the first graphics renderer that 
-        was available for MapServer, and it is required by MapServer to 
+        was available for MapServer, and was required by MapServer to 
         operate.
+
+        .. warning::
+
+          GD support was removed in Mapserver 7.0.
 
     GDAL
         GDAL (Geospatial Data Abstraction Library) is a multi-format raster