use reverse_proxy role, traefik for jitsi

docs/element.md

@@ -1,18 +1,22 @@
 # Required variables
-These variables are required. Example values included. Some general variables might also be required for this role.
+These variables are required. Example values included.
 
 ```
 ports:
   element_http: 8080
 
+element_domains: # not required if reverse_proxy_type is set to none
+  - chat.domain.tld
+  - element.domain.tld
+
 matrix_domain: domain.tld
 matrix_server_domain: matrix.domain.tld
 ```
 
+# Optional variables
 These variables are optional and have the following default values:
 ```
 matrix_external_url: https://{{ matrix_server_domain }}
-reverse_proxy_type: caddy
 
 jitsi_domain: jitsi.riot.im
 ```