Docs: Mention $router in "Programmatic Navigation" section

[fvictorio]

This may be obvious, but it took me some time to figure out.

I wanted to navigate programmatically in a component and it wasn't clear for me how to do it. The obvious answer is to use this.$router.go in a component method, but the "Programmatic Navigation" section in the documentation only refers to the "Router instance".

As far as I can tell, the only section that mentions the injected instance is the "Component injections" section.

Thanks.