Added an integrations page to the docs

docs/index.rst

@@ -97,6 +97,7 @@ Contents:
    hooks
    datamanager
    resourcemanager
+   integrations
    api
 
 

docs/integrations.rst

+Transaction integrations / Data Manager Implentations
+======================================================
+
+The following packages have been integrated with the ``transaction``
+package so that their transactions can be integerated with others.
+
+`ZODB <http://www.zodb.org>`_
+  ZODB was the original user of the ``transaction`` package.  Its
+  transactions are controlled by by ``transaction`` and ZODB fullt
+  implements the 2-phase commit protocol.