BUG-576: Fix concepts description
BUG-576: Fix concepts description

Fixes a copy-n-pasted description.

Change-Id: I8f3c92af7329f16e12d8201242ce8c4978a30de2
Signed-off-by: Robert Varga <b8bd3df785fdc0ff42dd1710c5d91998513c57ef@cisco.com>

opendaylight/yangtools,NovusTheory/yangtools,522986491/yangtools,opendaylight/yangtools