Add domain to domain redirect example (#273)

* Add domain to domain redirect example

* Added some debugging options

* remove line highlighting

* Apply suggestions from code review

Co-authored-by: ShadowArcanist <162910371+ShadowArcanist@users.noreply.github.com>

* Update redirects.md

---------

Co-authored-by: ShadowArcanist <162910371+ShadowArcanist@users.noreply.github.com>

Author: LucaNerlich

docs/knowledge-base/proxy/traefik/redirects.md

@@ -47,6 +47,26 @@ traefik.http.middlewares.example-middleware.redirectregex.replacement=${1}://www
 traefik.http.middlewares.example-middleware.redirectregex.permanent=true
 ```
 
+### domain -> other domain
+
+```bash
+traefik.http.middlewares.redirect-otherdomain.redirectregex.regex=^(https?://)?source-domain\.com(.*)
+traefik.http.middlewares.redirect-otherdomain.redirectregex.replacement=https://target-domain.com${2}
+traefik.http.middlewares.redirect-otherdomain.redirectregex.permanent=true
+```
+
+If you also need to generate a ssl cert for the target-domain, additionally add a routers entry
+
+```bash
+traefik.http.routers.redirect-otherdomain.middlewares=redirect-to-https
+traefik.http.routers.redirect-otherdomain.rule=Host(`target-domain.com`) && PathPrefix(`/`)
+traefik.http.routers.redirect-otherdomain.entryPoints=https
+traefik.http.routers.redirect-otherdomain.middlewares=redirect-otherdomain
+traefik.http.routers.redirect-otherdomain.rule=Host(`target-domain.com`) && PathPrefix(`/`)
+traefik.http.routers.redirect-otherdomain.tls.certresolver=letsencrypt
+traefik.http.routers.redirect-otherdomain.tls=true
+```
+
 ## Docker Compose based Applications & one-click Services
 
 - You need to set both FQDNs for your resource, so for example: `coolify.io,www.coolify.io`
@@ -67,3 +87,25 @@ traefik.http.middlewares.example-middleware.redirectregex.regex=^(http|https)://
 traefik.http.middlewares.example-middleware.redirectregex.replacement=${1}://www.${2}
 traefik.http.middlewares.example-middleware.redirectregex.permanent=true
 ```
+
+## Debugging
+
+You can check, if the traefik settings have been correctly applied, when inspecting your docker target container.
+
+Find your docker container id
+```bash
+docker ps
+```
+
+Inspect the containers labels
+
+```bash
+docker inspect <container-id>
+```
+
+You can additionally check the traefik container logs, by running
+
+```bash
+docker logs -f coolify-proxy
+```
+