Add note re case-sensitivity

Author: geographika

en/ogc/ogc_api.txt

@@ -464,7 +464,7 @@ Web Object Metadata
 
   The value supports :ref:`Run-time Substitution <runsub>`, where tokens in the form 
   ``%TOKEN%``, are replaced with validated values from the query string or cookies.
-  Parameters are validated against the rules in the :ref:`VALIDATION <validation>` block.
+  Parameters are validated against the rules in the :ref:`VALIDATION <validation>` block, and are case-insensitive.
   ``ows_extra_params`` can also be set at the ``LAYER`` ``METADATA`` level, for adding or overriding parameters at the collection-level.
   Example Mapfile: