Rollup merge of #75917 - poliorcetics:intra-doc-core-nonnull, r=jyn514
Rollup merge of #75917 - poliorcetics:intra-doc-core-nonnull, r=jyn514

Move to intra doc links for core::ptr::non_null

Helps with #75080.

@rustbot modify labels: T-doc, A-intra-doc-links, T-rustdoc

r? @jyn514

aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust