docker: Add depends_on long syntax (#1891)

Co-authored-by: Rico Sta. Cruz <rstacruz@users.noreply.github.com>

docker-compose.md

@@ -133,6 +133,16 @@ web:
     - db
 ```
 
+```yaml
+  # make sure `db` is healty before starting
+  # and db-init completed without failure
+  depends_on:
+    db:
+      condition: service_healthy
+    db-init:
+      condition: service_completed_successfully
+```
+
 ### Other options
 
 ```yaml