adjust 'authors' from scriblib/autobib so that it

has a contract (which I'm inferring from the way
it is implemented so I might be getting it wrong)

related to PR 12966

collects/scriblib/autobib.rkt

@@ -10,14 +10,19 @@
          (for-syntax syntax/parse
                      racket/base)
          scheme/string
-         setup/main-collects)
+         setup/main-collects
+         racket/contract)
 
 (provide define-cite
          author+date-style number-style
          make-bib in-bib (rename-out [auto-bib? bib?])
          proceedings-location journal-location book-location
          techrpt-location dissertation-location
-         author-name org-author-name authors other-authors editor)
+         author-name org-author-name 
+         (contract-out
+          [authors (->* (content?) #:rest (listof content?) element?)])
+         other-authors
+         editor)
 
 (define autobib-style-extras
   (let ([abs (lambda (s)

collects/scriblib/scribblings/autobib.scrbl

@@ -193,10 +193,11 @@ describing an author's name, especially where the last name is not
 merely a sequence of ASCII alphabet letters or where the name has a
 suffix (such as ``Jr.'').}
 
-@defproc[(authors [name any/c] ...) element?]{
+@defproc[(authors [name content?] [names content?] ...) element?]{
 
 Combines multiple author elements into one, so that it is rendered and
-alphabetized appropriately. If a @racket[name] is a string, it is
+alphabetized appropriately. Any of @racket[name] or @racket[names]
+that are strings are
 parsed in the same way as by @racket[make-bib].}
 
 @defproc[(org-author-name [name any/c]) element?]{