forc-doc implementations missing from sidebar and enums

[sdankel]

Example:

pub enum TestEnum {
    TestVariant: (),
}

impl TestEnum {
    pub fn test_fn() {}
}

impl Eq for TestEnum {
    fn eq(self, other: Self) -> bool {
        true
    }
}

The implementations don't show up in the sidebar nor in the page.

For structs, the implementations don't show up in the sidebar.