Description of Problem

After following all the steps from https://docs.redhat.com/en/documentation/red_hat_lightspeed/1-latest/html-single/connecting_your_rhel_systems_through_the_red_hat_lightspeed_proxy/index#proxy-installation-procedures , still the curl command fails to connect to the expected URLs through rhproxy , which is mentioned as the verifiation step in https://docs.redhat.com/en/documentation/red_hat_lightspeed/1-latest/html-single/connecting_your_rhel_systems_through_the_red_hat_lightspeed_proxy/index#adding_the_required_red_hat_hostnames_to_your_firewall_allowlist section.

How reproducible

(Always)

Steps to Reproduce

1. Install a RHEL 9.7 and connect it with redhat
2. Follow Chapter 2 to install and start rhproxy 
3. As mentioned in the Verification steps of 2.4.1 , use the curl command to verify connectivity to fedora mirror.

   curl -L -x http://$(hostname):3128 https://mirrors.fedoraproject.org/ 

Actual Behavior

curl: (56) Proxy CONNECT aborted

Received HTTP code 502 from proxy after CONNECT

Expected Behavior

No such errors.

Business Impact / Additional info

This happens as the rhproxy uses 1.1.1.1 DNS server as configured in /home/rhproxy/.config/rhproxy/env/rhproxy.env file and, nowhere in the docs we mention about updating the DNS config in this file, specifically , to make sure rhproxy works in user environments. Using 1.1.1.1 does not even works in RHs own environment. 

We can only make it work, after noticing https://docs.redhat.com/en/documentation/red_hat_lightspeed/1-latest/html-single/connecting_your_rhel_systems_through_the_red_hat_lightspeed_proxy/index#customizing-the-rhproxy-configuration and then fixing the value for RHPROXY_DNS_SERVER 

In my honest opinion, either the `rhproxy` command line should have a way to pass and override the default dns server entry or else the following sections of the doc i.e. 

3.5. Appendix B: Configuration options for the Red Hat Lightspeed proxy

3.2. Customizing the rhproxy configuration

should come up in the doc, before the curl-based verification step is documented.