Slightly improve docker-compose feedback (#2054)

docker-compose.yml

@@ -1,8 +1,7 @@
-# NOTE: This docker-compose.yml is meant to be just an example guideline
-# on how you can achieve the same. It is not intented to run out of the box
+# NOTE: This docker-compose.yml is an example setup.
+# It is not intented to run out of the box
 # and you must edit the below configurations to suit your needs.
-
-version: "3.7"
+# See https://listmonk.app/docs/installation/#manual-docker-install_1
 
 x-app-defaults: &app-defaults
   restart: unless-stopped

install-prod.sh

@@ -54,6 +54,11 @@ check_dependencies() {
 		echo "'docker compose' functionality is not available. Please update to a newer version of Docker. See https://docs.docker.com/engine/install/ for more details."
 		exit 1
 	fi
+
+	if ! docker compose ls >/dev/null; then
+		echo "no docker access - you might need to run this script with sudo or see https://docs.docker.com/engine/install/linux-postinstall/#manage-docker-as-a-non-root-user"
+		exit 1
+	fi
 }
 
 check_existing_db_volume() {