Fix creating a Docker network

Author: auguwu

template/main.tf

@@ -124,7 +124,8 @@ resource "coder_agent" "main" {
   fi
 
   if [ -n "${var.docker_network_name}" ]; then
-    docker network create "${var.docker_network_name}" --driver=bridge
+    docker network create "${var.docker_network_name}" --driver=bridge >/dev/null 2>&1
+    echo "Created Docker network \`${var.docker_network_name}\`, you can use it with .coder/docker-compose.yml as a external network! [$id]"
   fi
 
   # if ${var.workspace_dir}/.coder exists, then we will run the pre-init scripts