Review changelog

[jspaaks]

• consider reordering the sections to Changed, Added, Fixed such that they correspond with semver
• check that items are in the right section considering semver

[sdruskat]

Examples:

• Changed the regular expression for PMC ID to allow 8 digits in addition to the preexisting 7. Issue definitions.reference.pmcid should allow IDs with 8 digits #443; PR Update PMCID regex so it allows 8 chars #469 should be changed
• Allow references with only editors: Move to Added, see Make references with only editors citable #524 (comment).

[sdruskat]

• Add note to: Instances of person now explicitly require one of alias, email, given-names, family-names or orcid to avoid accidentally having empty person objects (notably, authors). PR https://github.com/citation-file-format/citation-file-format/pull/462 to say that although this is strictly speaking a breaking change, we consider this a bugfix as it allows non-sensible use of CFF, and the change will probably only affect very few people (with semantically invalid but version-valid files).