Include also contributors from other projects

[weihanglo]

According to this:

Currently, we are only tracking commits and reviews to rust-lang/rust and most of the related submodules. In the future, we have plans to add tracking for more repositories under the Rust project generally, and possibly even tracking other kinds of contributions, as they're also important!

We're not tracking other projects like Rustup and crates.io. However they are too essential to ignore. I'd like to see contributors from this projects got called out.

One issue is that the current thanks.rust-lang.org page groups contributors by Rust releases. Crates.io and rustup don't really follow the process. For rustup I think it might make sense to have a sub path for it, like https://thanks.rust-lang.org/rustup/1.28.0. I am not sure about crates.io. Maybe can group contributors by quaters.