Fix variable name typo

group_vars/matrix_servers

@@ -1025,7 +1025,7 @@ matrix_synapse_admin_enabled: false
 # Normally, matrix-nginx-proxy is enabled and nginx can reach Synapse Admin over the container network.
 # If matrix-nginx-proxy is not enabled, or you otherwise have a need for it, you can expose
 # Synapse Admin's HTTP port to the local host.
-matrix_synapse_admin_http_host_bind_port: "{{ '' if matrix_nginx_proxy_enabled else '127.0.0.1:8766' }}"
+matrix_synapse_admin_container_http_host_bind_port: "{{ '' if matrix_nginx_proxy_enabled else '127.0.0.1:8766' }}"
 
 ######################################################################
 #