c6017142a3
Switch to intra-doc links in core/src/{convert,iter}/mod.rs
Partial fix for #75080
@rustbot modify labels: T-doc, A-intra-doc-links, T-rustdoc
r? @jyn514
couldn't fix these
```rust
../../std/string/struct.String.html
../../std/primitive.never.html
../../std/sync/mpsc/struct.TryIter.html
```