phabricator: update the protocol documentation The `branch` property wasn't added to the `hg:meta` example when it was added to the metadata in d49ab47be8a6. Additionally, `properties` in the Differential Revision dict is a dinctionary, not a list. While here, also alphabetize the responses from Phabricator because that's how it is being printed with `hg debugcallconduit`, and this makes it easier to compare. Differential Revision: https://phab.mercurial-scm.org/D8170