Pick up change_note when building a document
Pick up change_note when building a document

This commit adds `change_note` as a field that is extracted from `publishing-api` responses when building a document. This allows it to be available when published documents are later presented to downstream systems.

alphagov/specialist-publisher-rebuild,alphagov/specialist-publisher-rebuild,alphagov/specialist-publisher-rebuild,alphagov/specialist-publisher,alphagov/specialist-publisher,alphagov/specialist-publisher-rebuild,alphagov/specialist-publisher