message: Fix doc test for format guess reading from memory
diff: @@ -31,16 +31,16 @@ use super::free_functions;
  /// source is some blob in memory and you have constructed the reader in another way. Here is an
  /// example with a `pnm` black-and-white subformat that encodes its pixel matrix with ascii values.
  ///
  -/// ```no_run
  +/// ```
  /// # use image::ImageError;
  /// # use image::io::Reader;
  /// # fn main() -> Result<(), ImageError> {
  /// use std::io::Cursor;
  /// use image::ImageFormat;
  ///
  -/// let raw_data = b"P1 2 2\
  -/// 0 1\
  -/// 1 0";
  +/// let raw_data = b"P1 2 2\n\
  +/// 0 1\n\
  +/// 1 0\n";
  ///
  /// let mut reader = Reader::new(Cursor::new(raw_data))
  /// .with_guessed_format()
  