PROTON-225: review feedback

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/branches/kgiusti-proton-225@1446333 13f79535-47bb-0310-9956-ffa450edef68
PROTON-225: more doc changes

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/branches/kgiusti-proton-225@1446334 13f79535-47bb-0310-9956-ffa450edef68