docs(ini): Clarify php.ini search order and additional .ini scan path in configuration docs

[joshtrichards]

Improve the php.ini configuration-file documentation to better match the implementation and make the loading process clearer.

This update:

• clarifies that the documented sequence refers to the primary configuration file,
• explains the distinction between a SAPI-provided override and the normal search-path construction,
• makes it clear that PHP looks for php-SAPI.ini before php.ini,
• and separates primary-file lookup from the later scan for additional .ini files via PHP_INI_SCAN_DIR or --with-config-file-scan-dir.

Same change in both production and development sample ini file.

[iluuu1994]

Honestly, I'm not totally convinced this is the right place to document this anyway. INI files are migrated from one PHP version to the next, and this documentation is bound to get outdated.

[iluuu1994]

I believe this is a bit more complicated. The ini override path is used both as a file name and path. Meaning, if a full file is specified, that file is used (e.g. for php-cgi -c /full/path/php.ini). However, a directory can also be specified, in which case PHP will still look for a php-{sapi}.ini and php.ini file in that directory.