message: Fix documentation of PNGReader
diff: @@ -16,8 +16,8 @@ use image::{ImageDecoder, ImageError, ImageResult};
  /// PNG Reader
  ///
  /// This reader will try to read the png one row at a time,
  -/// however for interlaced png files this is not posible and
  -/// these are therefore readed at once.
  +/// however for interlaced png files this is not possible and
  +/// these are therefore read at once.
  pub struct PNGReader<R: Read> {
  reader: png::Reader<R>,
  buffer: Vec<u8>,
  