Clarify what changes need a release note
Clarify what changes need a release note

This information is added to developer's FAQ.

Change-Id: Id615ee9ff50e6f8d7279c07ba31c5d9d31e399ef

SauloAislan/ironic,bacaldwell/ironic,ionutbalutoiu/ironic,dims/ironic,openstack/ironic,devananda/ironic,NaohiroTamura/ironic,NaohiroTamura/ironic,pshchelo/ironic,openstack/ironic,dims/ironic,ionutbalutoiu/ironic,bacaldwell/ironic,pshchelo/ironic,SauloAislan/ironic