message: Fix incorrect language tag.
diff: @@ -44,7 +44,7 @@ Features can list other features to enable. For example, the ICO image format
  can contain BMP and PNG images, so when it is enabled, it should make sure
  those other features are enabled, too:
  -```rust
  +```toml
  [features]
  bmp = []
  png = []
  