fix doc typo

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@27913 f0d54148-0727-0410-94bb-9a71ac55c965
fix broken link

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@27914 f0d54148-0727-0410-94bb-9a71ac55c965