update docker-compose for dependency handling

docker/docker-compose-db-nginx.yml

@@ -4,6 +4,8 @@ services:
     build:
       context: ./
     container_name: focalboard
+    depends_on:
+      - focalboard-db
     expose: 
       - 8000
     environment:

docker/docker-compose.yml

@@ -2,7 +2,7 @@ version: "3"
 services:
   app:
     build:
-      context: ./docker
+      context: ./
     container_name: focalboard
     ports: 
       - 80:8000