Override configuration files like: config.php

[mariajgrimaldi]

Description

I'm opening this issue to track the customization strategies for the LimeSurvey service, these are the ones we are currently considering:

• Adding my own configuration into config.php
• Adding my own Apache configurations in apache2.conf -> Is this useful?

Expected behavior

When adding a configuration into one of those files, I can set up how I want it to be.

Solution proposals

For this to work we could:

1. Create a configmap for the apache2.conf with some default values
2. Allow rendering config.php into the Dockerfile (check here why we can't use a configmap)