doc: update on direct host

Author: juliamrch

.github/assets/direct-host.png

@@ -1,10 +1,16 @@
 # NodeJS-PostgreSQL-Demo
 
-This is an example NodeJS application that works with PostgreSQL on Clever Cloud.
+This is an example Node.js application that works with PostgreSQL on Clever Cloud.
 
 The application is a very simple list where you can add or delete values.
 
 To install it, simply fork this repository and create an application from your GitHub repo.
 Then create a PostgreSQL add-on and link it to your application, either via the <a href="https://www.clever-cloud.com/doc/clever-tools/getting_started/" target="_blank">Clever Tools CLI</a> or via the <a href="https://console.clever-cloud.com/" target="_blank">Clever Cloud console</a>.
 
-That's it, the application will use the environnement variables to connect to the PostgreSQL DB.
+## Direct port and host
+
+Since this application can't run without connecting to a DB, ensure connections are quick by enabling direct port and host on your PostgreSQL add-on before deploying this app:
+
+![direct host and port creation on Clever Cloud console](.github/assets/direct-host.png)
+
+That's it, the application will use the `POSTGRESQL_ADDON_DIRECT_URI` environnement variable to connect to the PostgreSQL DB.