Repository: traefik/traefik (language: go)

Issue:
Documentation related to X-Forwarded headers: broken link & enhancements
### Welcome!

- [x] Yes, I've searched similar issues on [GitHub](https://github.com/traefik/traefik/issues) and didn't find any.
- [x] Yes, I've searched similar issues on the [Traefik community forum](https://community.traefik.io) and didn't find any.

### What did you expect to see?

Hi, 

it seems commit https://github.com/traefik/traefik/commit/b7170df2c3a37caaf8e68de5919a2013d9c7b928 broke the link in https://github.com/traefik/traefik/blob/master/docs/content/middlewares/http/headers.md (https://doc.traefik.io/traefik/v3.3/middlewares/http/headers/) added in https://github.com/traefik/traefik/commit/8e7881094f1d8fe20a95855f74b6d5028e5b9f00.

The new location is in https://github.com/traefik/traefik/blob/master/docs/content/reference/routing-configuration/http/middlewares/headers.md (https://doc.traefik.io/traefik/v3.3/reference/routing-configuration/http/middlewares/headers/).

Also, maybe a link between (from and to) this new location and https://doc.traefik.io/traefik/v3.3/routing/entrypoints/#forwarded-headers (https://github.com/traefik/traefik/blob/master/docs/content/routing/entrypoints.md#forwarded-headers) could be added, as those informations is not so easy to find (& seems pretty useful to me)?

Also, maybe add precisions on what happens if `forwardedHeaders.trustedIPs` is not set (which I believe is headers are [removed](https://github.com/traefik/traefik/blob/v3.3.4/pkg/middlewares/forwardedheaders/forwarded_header.go#L189)), and what happens if client from `forwardedHeaders.trustedIPs` already set `X-Forwarded-For` (or another header; which I believe is ~append to the existing field~ simply fill or copy, see https://github.com/traefik/traefik/blob/v3.3.4/pkg/middlewares/forwardedheaders/forwarded_header_test.go)?

Best,


Discussion / hints:

Fix patch:
diff --git a/docs/content/getting-started/faq.md b/docs/content/getting-started/faq.md
index 1c3d3f6a8b..66f2d4d046 100644
--- a/docs/content/getting-started/faq.md
+++ b/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


Test patch: