feat(post): add docker persistent storage for ghost files

docker-compose.yml

@@ -78,6 +78,8 @@ services:
       database__connection__database: ghost
       # this url value is just an example, and is likely wrong for your environment!
       url: http://localhost:${GHOST_PORT}
+    volumes:
+      - ghost-content:/var/lib/ghost/content
 
   ghost-db:
     image: mysql:5.7
@@ -126,6 +128,8 @@ volumes:
     driver: local
   db-elastic:
     driver: local
+  ghost-content:
+    driver: local
 
 networks:
   backend: