Add DOI, PMID and PMCID to Council of Science Editors

Add DOI, PMID and PMCID to the "notes" section. The 8th ed. says that these can be added there (29.3.6.13.10).
please put these in a group with delimiter=". " -- that's more robust and e.g. avoids the double space that you currently get when there's a PMID but no DOI (which e.g. Zotero will take out automatically, but we shouldn't rely on that when it's not necessary).