OAK-301 : clarification about the indexed types in lucene

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1601827 13f79535-47bb-0310-9956-ffa450edef68
OAK-1862 - Checkpoints release method

Implementing release support for DocumentNodeStore

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1601833 13f79535-47bb-0310-9956-ffa450edef68