Documentation Out of Date

[JamesDConley]

The config walkthrough at https://github.com/kubernetes-sigs/prometheus-adapter/blob/master/docs/config-walkthrough.md hasn't been updated for four years, and I haven't managed to get prometheus adapter running while trying to follow it. Some of the examples provided me errors that prevented the system from being deployed.

If there's better documentation please do let me know as I've been really fumbling through this.