Document that we should not use `PHP_INI_SCAN_DIR`

[Nyholm]

If we override PHP_INI_SCAN_DIR then the "special php.ini" files will not be used. Ie: https://github.com/brefphp/bref/blob/0.5.9/runtime/layers/fpm/php.ini

[jenschude]

Or that at least a sane value should be used:

https://github.com/brefphp/bref/blob/master/runtime/layers/fpm-dev/Dockerfile#L32

[fredericgboutin-yapla]

aka - the doc should probably give an example like PHP_INI_SCAN_DIR=:/var/task/my_codebase/_my_custom_path (with the : at the beginning) - see https://www.php.net/manual/en/configuration.file.php

UPDATE: somehow it doesn't work and you have to explicitly set the original path, PHP_INI_SCAN_DIR=/opt/bref/etc/php/conf.d:/var/task/my_codebase/_my_custom_path - thanks https://github.com/brefphp/bref/issues/1363#issuecomment-1358008629 🎉