Rollup merge of #45245 - stjepang:more-padding-between-impls, r=QuietMisdreavus
Rollup merge of #45245 - stjepang:more-padding-between-impls, r=QuietMisdreavus

Rustdoc: Increase padding between consecutive impls

Currently, [implementors](https://doc.rust-lang.org/nightly/std/iter/trait.IntoIterator.html#implementors) list is a bit too condensed. More spacing makes the list easier to read.
Check out [this comment](https://github.com/rust-lang/rust/issues/41879#issuecomment-333121118) to see what's the effect of this change.

Closes #41879.

cc @QuietMisdreavus

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