portfolio/smartevidence: Make inst. setting clearer

Link to the institution settings so its easier to find
where SmartEvidence needs to be allowed for an
institution.

source/portfolio/smartevidence.rst

@@ -29,6 +29,9 @@ Select a framework
 
 When an institution allows SmartEvidence, any user in that institution can work with the frameworks that are available. The framework is selected on the collection's *Edit* screen for institution or personal collections.
 
+.. note::
+   Your institution administrator needs to allow SmartEvidence in the :ref:`institution settings <add_institution>` before you can use this feature.
+
 .. figure:: /images/collection_create.*
    :alt: Create a collection