Including suppress author, in text, etc

[bdarcus]

Another issue I've confused myself about, which makes me think we should document:

The core citation and/or citation variants that most processors implement, but aren't here:

• suppress author
• author-in-text/narrative
• author-only
• ?

[tillgrallert]

I'd like to push this issue. The absent documentation of these features makes behaviours hard to debug!