Auto merge of rust-lang#104292 - GuillaumeGomez:fix-missing-reexports-doc-comments, r=notriddle

Fix missing reexports' doc comments

Fixes rust-lang#81893.

The issue was that an import directly "links" to the target without the intermediate imports. Unfortunately, to fix this bug we need to go through them one by one. To do so, I take the import path direct parent (so `b` in `a::b::c`) and then look for `c` into it.

r? `@notriddle`

Author: bors