DOC: Extend ROCrateEntityConverter explanation

src/doc/converters/further_converters.rst

@@ -132,8 +132,16 @@ File object, which can be matched with SimpleFile. And each subpart of the
 ROCrateEntity is also converted to a ROCrateEntity, which can then again be
 treated using this converter.
 
-To match a ROCrateEntity using its entity_type, the match_entity_types keyword
-can be used.
+The ``match_entity_type`` keyword can be used to match a ROCrateEntity using its
+entity_type. With the ``match_properties`` keyword, properties of a ROCrateEntity
+can be either matched or extracted, as seen in the cfood example below:
+* with ``match_properties: "@id": ro-crate-metadata.json`` the ROCrateEntities
+can be filtered to only match the metadata json files.
+* with ``match_properties: dateCreated: (?P<dateCreated>.*)`` the ``dateCreated``
+entry of that metadata json file is extracted and accessible through the
+``dateCreated`` variable.
+* the example could then be extended to use any other entry present in the metadata
+json to filter the results, or insert the extracted information into generated records.
 
 Example cfood
 -------------