Examples that use `.` for improper lists render incorrectly

[florence]

The examples at

https://github.com/racket/racket/blob/master/pkgs/racket-doc/scribblings/reference/hashes.scrbl#L596

make hash tables like: (make-immutable-hash '([1 . (one uno)] [2 . (two dos)]))

however the documentation renders this as:

(make-immutable-hash '([1    one uno]  [2    two dos]))

(with the extra spaces between the keys and the values).

Unfortunately this makes those docs a little confusing to read... I'm guessing this happens because read-syntax doesn't preserve the ., but I'm not sure how to go about fixing, since there doesn't seem to be a syntax property that says "dot goes here".