Fix doc bug reported by insaneinside on IRC.
Fix doc bug reported by insaneinside on IRC.

SeanRBurton/regex,rust-lang/regex,rust-lang/regex,SeanRBurton/regex,golddranks/regex,rust-lang-nursery/regex,rust-lang/regex,SeanRBurton/regex,rust-lang-nursery/regex,rust-lang/regex,rust-lang-nursery/regex,rust-lang-nursery/regex,SeanRBurton/regex,rust-lang/regex,SeanRBurton/regex,golddranks/regex,golddranks/regex,rust-lang-nursery/regex