MAGECLOUD-3357: [Cloud Docker] Changes in .magento.app.yaml should affect php modules

guides/v2.1/cloud/docker/docker-development-debug.md

@@ -18,7 +18,20 @@ If you use Microsoft Windows, take the following steps before continuing:
 
 ## Enable Xdebug
 
-To enable Xdebug, you must configure your `docker-compose.yaml` file at the time you configure your local workstation to [Launch Docker]({{ page.baseurl }}/cloud/docker/docker-config.html).
+To enable Xdebug, you must add `xdebug` to `.magento.app.yaml` file.
+```yaml
+# Enable extensions required by Magento 2
+runtime:
+    extensions:
+        - redis
+        - xsl
+        - json
+        - blackfire
+        - newrelic
+        - xdebug
+
+```
+After, you must rebuild your `docker-compose.yaml` file, using cli command `php ./vendor/bin/ece-tools docker:build` at the time you configure your local workstation to [Launch Docker]({{ page.baseurl }}/cloud/docker/docker-config.html).
 
 ```yaml
 generic: