Add back forwarded headers section in FAQ

docs/content/getting-started/faq.md

@@ -143,6 +143,21 @@ To take into account the new certificate contents, the update of the dynamic con
 One way to achieve that, is to trigger a file notification,
 for example, by using the `touch` command on the configuration file.
 
+## What Are the Forwarded Headers When Proxying HTTP Requests?
+
+By default, the following headers are automatically added when proxying requests:
+
+| Property                  | HTTP Header                |
+|---------------------------|----------------------------|
+| Client's IP               | X-Forwarded-For, X-Real-Ip |
+| Host                      | X-Forwarded-Host           |
+| Port                      | X-Forwarded-Port           |
+| Protocol                  | X-Forwarded-Proto          |
+| Proxy Server's Hostname   | X-Forwarded-Server         |
+
+For more details,
+please check out the [forwarded header](../routing/entrypoints.md#forwarded-headers) documentation.
+
 ## How Traefik is Storing and Serving TLS Certificates?
 
 ### Storing TLS Certificates