d33e1916ce
Clarify/fix formatting docs concerning fmt::Result/fmt::Error 1. `fmt::Result` != `io::Result<()>` 2. Formatters should only propagate errors, not return their own. Confusion on reddit: https://www.reddit.com/r/rust/comments/4yorxr/is_implt_tostring_for_t_where_t_display_sized_a/