Prepare backend for frontend integration

.env.example

@@ -1,5 +1,5 @@
-# Host port of the Drivers Hub API.
-HUB_PORT=7777
+# Address and port on the Docker host.
+BACKEND_BIND=127.0.0.1:17777
 
 DB_NAME=drivershub
 DB_PASSWORD=replace-with-a-long-random-password