Add html_root_url for core and futures, with a reminder in Cargo.toml

[smt923]

Should close #424 - I've used some shorter version links for the docs, but if I should just make these exactly what version is specified in the Cargo.toml I can change it, those versions just don't have any published docs yet and making a PR with links that 404'd didn't feel right (but perhaps this is totally fine)

[smt923]

I'm not sure if this is 'okay' or not, the cargo version is 0.1.0, but the only docs up are 0.0.1

[KodrAus]

Thanks @smt923!

I think the version of rayon-futures on crates.io (which is what docs.rs would build from) are just a placeholder. The 0.1.0 version here hasn't been released yet, but I think it's ok to point the html_root_url at the version that will be, so we don't forget to update it when releasing 0.1 later.

[KodrAus]

Thanks @smt923!

I think the version of rayon-futures on crates.io (which is what docs.rs would build from) are just a placeholder. The 0.1.0 version here hasn't been released yet, but I think it's ok to point the html_root_url at the version that will be, so we don't forget to update it when releasing 0.1 later.

[KodrAus]

Let's make this 0.1 so it's in line with what's in the Cargo.toml, even if that hasn't been released yet.

[KodrAus]

This looks good to me!

[KodrAus]

This looks good to me!

[cuviper]

Thanks!