Remove note about transmute for float bitpatterns.
This particular usecase has been safely abstracted in these `std` functions: [f32::to_bits](https://doc.rust-lang.org/std/primitive.f32.html#method.to_bits), [f32::from_bits](https://doc.rust-lang.org/std/primitive.f32.html#method.from_bits), [f64::to_bits](https://doc.rust-lang.org/std/primitive.f64.html#method.to_bits), [f64::from_bits](https://doc.rust-lang.org/std/primitive.f64.html#method.from_bits). So, I think we shouldn't recommend an unnecessary use of `unsafe` here anymore.
///
/// There are a few things that `transmute` is really useful for.
///
- /// Getting the bitpattern of a floating point type (or, more generally,
- /// type punning, when `T` and `U` aren't pointers):
- ///
- /// ```
- /// let bitpattern = unsafe {
- /// std::mem::transmute::<f32, u32>(1.0)
- /// };
- /// assert_eq!(bitpattern, 0x3F800000);
- /// ```
- ///
/// Turning a pointer into a function pointer. This is *not* portable to
/// machines where function pointers and data pointers have different sizes.
///