docs cpointers over place-channels

collects/scribblings/foreign/cpointer.scrbl

@@ -31,10 +31,6 @@ the tag is a pair, its first value is used for printing, so the most
 recently pushed tag which corresponds to the inheriting type will be
 displayed.
 
-Note that tags are compared with @racket[eq?] (or @racket[memq]), which means
-an interface can hide its value from users (e.g., not provide the
-@racket[cpointer-tag] accessor), which makes such pointers un-fake-able.
-
 @racket[_cpointer/null] is similar to @racket[_cpointer] except that
 it tolerates @cpp{NULL} pointers both going to C and back.  Note that
 @cpp{NULL} pointers are represented as @racket[#f] in Racket, so they

collects/scribblings/reference/places.scrbl

@@ -223,7 +223,10 @@ messages:
        immutable vector;}
 
  @item{@tech{place channels}, where a @tech{place descriptor} is
-       automatically replaced by a plain place channel; and}
+       automatically replaced by a plain place channel;}
+
+ @item{foreign pointers such as @racket[_cpointers] and 
+       cstructs; and}
 
  @item{values produced by @racket[shared-flvector],
        @racket[make-shared-flvector], @racket[shared-fxvector],