message: Fixed documentation for `now`
  Closes
diff: @@ -394,7 +394,7 @@ fn keys(obj: {}) -> [str] { ... }
  fn chars(text: str) -> [str] { ... }
  /// Returns seconds since last Unix Epoch.
  -/// Returns `err(_)` if system clock is adjusted before Unix Epoch.
  +/// Returns a negative number if system clock is adjusted before Unix Epoch.
  fn now() -> f64 { ... }
  /// Returns `true` if number is NaN.
  