Document how to set up management console behind reverse proxy

Created by: djuarezg

Question description

How should we configure an Apache proxy to work with the management console.

Is your question related to a problem? If so, please describe or link to another issue.

We configured a proxy in front on Sourcegraph, but after the upgrade to 3.X we have to configure access to the management console as well, which uses basic auth.

The problem is that the configuration update does not happen due to Unexpected HTTP 401: Unauthorized

The request does not send any cookie or basic auth as a parameter/header.