Add Traefik setup, incl. step-by-step, to docker README.

docker/docker-compose.traefik.yml

@@ -41,6 +41,16 @@ services:
             # CONDUIT_WORKERS: 10
             # CONDUIT_MAX_REQUEST_SIZE: 20_000_000  # in bytes, ~20 MB
 
+    # We need some way to server the client and server .well-known json. The simplest way is to use a nginx container
+    # to serve those two as static files. If you want to use a different way, delete or comment the below service, here
+    # and in the docker-compose override file.
+    well-known:
+        image: nginx:latest
+        restart: unless-stopped
+        volumes:
+            - ./nginx/matrix.conf:/etc/nginx/conf.d/matrix.conf # the config to serve the .well-known/matrix files
+            - ./nginx/www:/var/www/ # location of the client and server .well-known-files
+
     ### Uncomment if you want to use your own Element-Web App.
     ### Note: You need to provide a config.json for Element and you also need a second
     ###       Domain or Subdomain for the communication between Element and Conduit