Docs linkage

[logannc]

https://blog.rust-lang.org/2020/11/19/Rust-1.48.html#easier-linking-in-rustdoc

pub mod foo {
    /// Some docs for `Foo`
    ///
    /// You may want to use `Foo` with [`Bar`].
    ///
    /// [`Bar`]: ../bar/struct.Bar.html
    pub struct Foo;
}

pub mod bar {
    /// Some docs for `Bar`
    ///
    /// You may want to use `Bar` with [`Foo`].
    ///
    /// [`Foo`]: ../foo/struct.Foo.html
    pub struct Bar;
}

We do reference other functions and things in docs, it would be good to add linkage.