Update 5_4.md

Add docker-compose requirement

5_zero2prod/5_chapter/5_4.md

@@ -1 +1,2 @@
-Package your app from the previous exercises into a docker container.
+1. Package your app from the previous exercises into a docker container.
+2. Add a docker-compose configuration to properly configure needed infrastructure (like DB, volumes, network, and so on).