Remove unnecessary links

.examples/docker-compose/insecure/mariadb-cron-redis/apache/docker-compose.yml

@@ -25,18 +25,12 @@ services:
       - nextcloud:/var/www/html
     env_file:
       - db.env
-    links:
-      - db
-      - redis
 
   cron:
     build: ./app
     restart: always
     volumes:
       - nextcloud:/var/www/html
-    links:
-      - db
-      - redis
     user: www-data
     entrypoint: |
       bash -c 'bash -s <<EOF

.examples/docker-compose/insecure/mariadb/apache/docker-compose.yml

@@ -21,8 +21,6 @@ services:
       - nextcloud:/var/www/html
     env_file:
       - db.env
-    links:
-      - db
 
 volumes:
   db:

.examples/docker-compose/insecure/postgres/apache/docker-compose.yml

@@ -18,8 +18,6 @@ services:
       - nextcloud:/var/www/html
     env_file:
       - db.env
-    links:
-      - db
 
 volumes:
   db: