Rollup merge of #142101 - lolbinarycat:core-dedup-ptr-docs-139190-pt2, r=workingjubilee

core::ptr: deduplicate more method docs

used `rg -Fxf library/core/src/ptr/{const,mut}_ptr.rs` to find duplicated doc comments, and `diff -u` after copying them to files to ensure they are actually identical.

`sed 's| */// *||'` was then used to translate the doc comments to plain markdown.

part of rust-lang/rust#139190

Author: fmease