Fix incorrect variable name in docs/howto-srv-server-delegation.md (traefik_environment_variables -> traefik_environment_variables_additional_variables)

Ref: a008706c32/defaults/main.yml (L109-L115)

docs/howto-srv-server-delegation.md

@@ -73,7 +73,7 @@ traefik_configuration_extension_yaml: |
         storage: {{ traefik_config_certificatesResolvers_acme_storage | to_json }}
 
 # 2. Configure the environment variables needed by Rraefik to automate the ACME DNS Challenge (example for Cloudflare)
-traefik_environment_variables: |
+traefik_environment_variables_additional_variables: |
   CF_API_EMAIL=redacted
   CF_ZONE_API_TOKEN=redacted
   CF_DNS_API_TOKEN=redacted
@@ -153,7 +153,7 @@ traefik_configuration_extension_yaml: |
 traefik_certResolver_primary: "dns"
 
 # Configure the environment variables needed by Traefik to automate the ACME DNS Challenge (example for Cloudflare)
-traefik_environment_variables: |
+traefik_environment_variables_additional_variables: |
   CF_API_EMAIL=redacted
   CF_ZONE_API_TOKEN=redacted
   CF_DNS_API_TOKEN=redacted