Docker proxy settings

[eero-t]

Many docs in this repo instruct giving HTTP/S proxies on Docker build command line:

$ git grep -e "--build-arg.*https*_proxy=" | wc -l
58

IMHO it would be better to just specify them once in Docker config, like this:

$ cat ~/.docker/config.json`
...
	"proxies": {
		"default": {
			"httpProxy": "http://proxy-chain.foobar.com:911",
			"httpsProxy": "http://proxy-chain.foobar.com:911",
			"noProxy": "localhost,127.0.0.1/8,::1,192.168.0.0/16,10.244.0.0/16"
		}
	}
}