docker: Add blank lines between services

to make the file a bit easier on the eyes ;)

Author: Turbo87

docker-compose.yml

@@ -1,4 +1,5 @@
 version: "3"
+
 services:
   postgres:
     image: postgres:9.6
@@ -10,6 +11,7 @@ services:
       - 5432:5432
     volumes:
       - postgres-data:/var/lib/postgresql/data
+
   backend:
     build:
       context: .
@@ -34,6 +36,7 @@ services:
       - index:/app/tmp
       - cargo-cache:/usr/local/cargo/registry
       - target-cache:/app/target
+
   frontend:
     build:
       context: .