update postgresql json to add post install password setup (#1318)

json/postgresql.json

@@ -30,5 +30,10 @@
         "username": null,
         "password": null
     },
-    "notes": []
+    "notes": [
+        {
+            "text": "Set a password after installation for postgres user by running `echo \"ALTER USER postgres with encrypted password 'your_password';\" | sudo -u postgres psql`",
+            "type": "info"
+        }
+    ]
 }