documente un souci avec docker lors de l'installation de chill

docs/source/installation/index.rst

@@ -65,6 +65,17 @@ This script will :
 4. build assets
 
 
+.. note::
+
+   In some cases it can happen that an old image (chill_base_php or chill_php) stored in the docker cache will make the script fail. To solve this problem you have to delete the image and the container, before the make init :
+
+.. code-block:: bash
+
+   docker-compose images php
+   docker rmi -f chill_php:prod
+   docker-compose rm php
+
+
 4. Start the project
 ====================