Fix HTTP 403 (Forbidden) errors

Currently, the Apache server attempts to use port 9000 on the php container for handling PHP files and loads all other files from /var/www/html - however, /var/www/html does not exist in the Apache container.

This results in the following error:

Forbidden

You don't have permission to access this resource.

The web files from the php container should be shared with the Apache container, mounted at /var/www/html. A volume called www-data should be mounted on the php container and then mounted on the Apache container at /var/www/html. This allows both the containers to access these files.