Doc: an error in an example

[sorawee]

One example program in the documentation is:

'(q () (q ((page-margin-left "120") (page-margin-top "80") (page-margin-bottom "120") (font-family "text") (line-height "17")) (q ((keep-first-lines "2") (keep-last-lines "3") (font-size "100%") (character-tracking "0") (hyphenate "true") (display "g49598")) "Brennan and Dale like fancy sauce.")))

But running this gives the following error:

../git/quad/quadwriter/lang-helper.rkt:82:30: *: contract violation
  expected: number?
  given: "100%"
  argument position: 1st
  other arguments...:

Note that when I run

#lang quadwriter/markdown
Brennan and Dale like fancy sauce.

the output doc has (font-size "1em") instead

[mbutterick]

Thanks!