Rollup merge of #76238 - denisvasilik:intra-doc-links-core-iterator, r=jyn514
Move to intra-doc links for library/core/src/iter/traits/iterator.rs
Helps with #75080.
@jyn514 We're almost finished with this issue. Thanks for mentoring. If you have other topics to work on just let me know, I will be around in Discord.