Starting point for new contributors, some issues

Hey,

as I was checking docs yesterday I wanted to "simulate" a road for new contributors to be able to help with a project using Docker, those are my Issues.

Everything based on documentation

1. memory_limit is way too low https://github.com/PrestaShop/docker/blob/master/base/config_files/php.ini#L393 - I wasn't able to go through first steps of the Installer scripts because of this
2. For me, on MacOS Catalina Installer script completely doesn't work because of an issue with modules installation/update.
   Error:

Next GuzzleHttp\Exception\RequestException: SSL CA bundle not found: /var/www/html/var/cache/dev/cacert.pem in /var/www/html/vendor/guzzlehttp/guzzle/src/Exception/RequestException.php:51

By default PrestaShop generates cacert.pem but we don't have it for Installer script, maybe it's related to next issue...

3. Just to make sure that it's not CLI installer fault I went to:
   http://localhost:8001/install-dev/index.php
   Unfortunately there are two issues:

• no proper /var/cache chmods
• no intl extension (but it's not blocking error)

I'm going to improve documentation because we miss many useful informations, how to change installation options, disable assets creation (after refreshing container) etc. but I'm wondering what can we do about this issue with SSL CA bundle? I was trying to manually copy this file, set proper chmods for var/cache but w/o success 🤔

One more question, suggestion, what y'all think about adding "docker_run_before.sh", and "docker_run_after.sh"? (bafter build, before enabling network)

Start with the linked Docker installation documentation, then inspect base/config_files/php.ini at line 393 and reproduce the installer flow through install-dev/index.php. Check the reported SSL CA bundle, var/cache permissions, and intl-extension errors; done would require a clearly scoped fix or documented resolution for the affected Docker installation path.