Fix contract docs for departments in scribble/acmart.

(I placed the wrong contract in the docs. The correct one is the one
defined in the module.)

scribble-doc/scribblings/scribble/acmart.scrbl

@@ -146,7 +146,7 @@ screen version of the image links to the badge authority.
 
 @defproc[(affiliation
           [#:position position (or/c pre-content? #f) #f]
-          [#:institution institution (or/c pre-content? institution? #f) #f]
+          [#:institution institution (listof (or/c pre-content? institution?)) '()]
           [#:street-address street-address (or/c pre-content? #f) #f]
           [#:city city (or/c pre-content? #f) #f]
           [#:state state (or/c pre-content? #f) #f]

scribble-lib/scribble/acmart.rkt

@@ -289,7 +289,6 @@
   (define (mk-inst name
                    #:department? [department? department?]
                    #:level [level level])
-    (displayln department?)
     (case department?
       [(#f) (make-element (make-style "institution" command-props)
                           (decode-content name))]