`transmute_ref` doc example fails to compile as-written

This hidden type alias in the doctest for `transmute_ref!`
```
/// # type u16 = zerocopy::byteorder::native_endian::U16;
/// # type u32 = zerocopy::byteorder::native_endian::U32;
```
exceeds the threshold of sensible cleverness by suggesting that `transmute_ref` somehow bypasses the usual shortcomings of alignedness and `IntoBytes`. Whatever example is used here should *basically* compile as-written.