docs: missing -wait

typo found by @thejck

Author: buchdag

docs/Docker-Compose.md

@@ -75,7 +75,7 @@ services:
   docker-gen:
     image: nginxproxy/docker-gen
     container_name: nginx-proxy-gen
-    command: -notify-sighup nginx-proxy -watch 5s:30s /etc/docker-gen/templates/nginx.tmpl /etc/nginx/conf.d/default.conf
+    command: -notify-sighup nginx-proxy -watch -wait 5s:30s /etc/docker-gen/templates/nginx.tmpl /etc/nginx/conf.d/default.conf
     volumes_from:
       - nginx-proxy
     volumes: