Rollup merge of #144072 - usamoi:docs, r=Mark-Simulacrum

update `Atomic*::from_ptr` and `Atomic*::as_ptr` docs

Since rust-lang/rust#128778, it's allowed to perform atomic read and non-atomic read on the same atomic at the same time. Update the `Atomic*::from_ptr` and `Atomic*::as_ptr` documentation to remove expressions such as `not allowed to mix atomic and non-atomic accesses`.

see also [std::sync::atomic](https://doc.rust-lang.org/std/sync/atomic/index.html#memory-model-for-atomic-accesses)

Author: matthiaskrgr