Extra 20px left margin applied to typedef'd return types

[sfackler]

http://sfackler.github.io/rust-postgres/doc/postgres/struct.Row.html

[frewsxcv]

Looks like it got added in 0a46933#diff-e0f884b85741a0964cc4b7722e0e6fadR351

[bluss]

I think using .content .impl-items > .type would fix it to only apply to associated types, not type aliases in other positions (return value)