I made an extension that notifies you in VS Code when there is an update available to the stable version of Rust.
It is essentially a wrapper that runs 'rustup check' for you. You can also configure it to auto-update Rust stable if you want.
The extension runs once you first open a Rust file in a given VS code instance. Opening additional files in the same VS code instance will not cause the extension to run again.
Hopefully, other people will also find this useful 
You can find and install it in VS Code directly via the extensions tab.
Marketplace page: RustUp Reminder - Visual Studio Marketplace .
