rustdoc shows auto impls for `[u8]`

https://doc.rust-lang.org/nightly/std/marker/trait.Send.html#impl-Send-80

this is pretty confusing as there also exists an auto impl for `[T]` https://doc.rust-lang.org/nightly/std/marker/trait.Send.html#impl-Send-429

I expect that rustdoc incorrectly treats the `impl [u8]` impl as a distinct type or something like this... not completely sure
