Setup link is broken

1. Setup link

From the paragraph on https://www.chisel-lang.org

> Build Your Own Chisel Projects
> See [the setup instructions](https://www.chisel-lang.org/SETUP.md) for how to set up your environment to build Chisel locally.

the link https://www.chisel-lang.org/SETUP.md is broken.
https://github.com/chipsalliance/chisel3/blob/master/SETUP.md would work.

2. Yosys link

It should be https://github.com/YosysHQ/yosys not https://clifford.at