DOC: Extend blacklist explanation

src/doc/converters.rst

@@ -334,8 +334,13 @@ property:
 .. image:: img/properties-from-dict-records-person.png
   :height: 200
 
+For the time being, only the parents of the referenced record can be
+set via this option. More complicated treatments can be implemented
+via the ``referenced_record_callback`` (see below).
+
 Properties can be blacklisted with the ``properties_blacklist``
-keyword. Since the
+keyword, i.e., all keys listed under ``properties_blacklist`` will be
+excluded from automated treatment. Since the
 :py:class:`~caoscrawler.converters.PropertiesFromDictConverter` has
 all the functionality of the
 :py:class:`~caoscrawler.converters.DictElementConverter`, individual
@@ -343,7 +348,10 @@ properties can still be used in a subtree. Together with
 ``properties_blacklist`` this can be used to add custom treatment to
 specific properties by blacklisting them in ``record_from_dict`` and
 then treating them in the subtree the same as you would do it in the
-standard :py:class:`~caoscrawler.converters.DictElementConverter`.
+standard
+:py:class:`~caoscrawler.converters.DictElementConverter`. Note that
+the blacklisted keys are excluded on **all** levels of the dictionary,
+i.e., also when they occur in a referenced entity.
 
 For further customization, the
 :py:class:`~caoscrawler.converters.PropertiesFromDictConverter` can be