Added release dates for gis libs as doc comments

docs/ref/contrib/gis/install/geolibs.txt

@@ -18,6 +18,25 @@ Program                   Description                           Required
 `SpatiaLite`__            Spatial extensions for SQLite         Yes (SQLite only)                 3.0, 2.4, 2.3
 ========================  ====================================  ================================  ==========================
 
+..
+    Libs release dates:
+    GEOS 3.0.0 2008-08-14
+    GEOS 3.1.0 2009-03-11
+    GEOS 3.2.0 2009-12-14
+    GEOS 3.3.0 2011-05-30
+    GDAL 1.5.0 2007-12-20
+    GDAL 1.6.0 2008-12-04
+    GDAL 1.7.1 2010-02-08
+    GDAL 1.8.0 2011-01-13
+    GDAL 1.9.0 2012-01-03
+    PostGIS 1.3.0 2007-08-09
+    PostGIS 1.4.0 2009-07-24
+    PostGIS 1.5.0 2010-02-04
+    PostGIS 2.0.0 2012-04-03
+    SpatiaLite 2.3.0 2009-04-06
+    Spatialite 2.4.0 2010-11-14
+    Spatialite 3.0.0 2011-12-30
+
 .. admonition::  Install GDAL
 
     While :ref:`gdalbuild` is technically not required, it is *recommended*.