Update ProQuest.js

See https://forums.zotero.org/discussion/40821/zotero-not-recognizing-books-chapters-dissertations-in-proquest-psycinfo/

(Maybe we should wait for more examples of different types.)
I really like manuscript for unpublished and grey literature. It has, e.g., a "Type" field, so that you can describe what it actually is in the citation.