better documentation of new feature

CHANGES.rst

@@ -10,7 +10,7 @@ Breaking changes:
 
 New features:
 
-- addresses #4, allows third party software to define which indexes are used.
+- Adresses `Still uses BTrees wrongly, screws up people changing Interfaces <https://github.com/zopefoundation/z3c.relationfield/issues/4>`_, allows third party software to define which indexes are used.
   [jensens]
 
 Bug fixes:

setup.py

@@ -16,7 +16,7 @@ def read(*rnames):
 
 setup(
     name='z3c.relationfield',
-    version='0.7.2.dev0',
+    version='0.8.0.dev0',
     description="A relation field framework for Zope 3.",
     long_description=long_description,
     classifiers=[

src/z3c/relationfield/README.rst

@@ -874,3 +874,12 @@ It's pointing to the nonexistent path:
 
   >>> root['e'].rel.to_path
   'nonexistent'
+
+Setting up a releation catalog
+==============================
+
+This package provides a RelationCatalog initialized with a set of indexes commonly useful for queries on RelationValue objects.
+The default indexes are `from_id`, `to_id`, `from_attribute`, `from_interfaces_flattened` and `to_interfaces_flattened`.
+
+However, sometimes it is needed to define custom indexes.
+The `zc.relationfield.index.RelationCatalog` class can be initialized with a list of dicts with keys `name` and `kwargs` to be passed to RelationCatalog to be passed to the catalogs `addValueIndex` method.

src/z3c/relationfield/index.py

@@ -52,9 +52,9 @@ def load(token, catalog, cache):
 class RelationCatalog(Catalog):
 
     def __init__(self, indexes=DEFAULT_INDEXES):
-        """initialize the catalog with indexes.with
+        """Initialize the catalog with indexes.
 
-        Uses defaults if not special configuration was passed.was
+        Uses defaults if not special configuration was passed.
         """
         Catalog.__init__(self, dump, load)
         for index in indexes: