[DOC] PHP provider docu on flagd.dev is missing the PHP minimal version

[alexlehm]

Change in the documentation

in the file https://github.com/open-feature/php-sdk-contrib/blob/main/providers/Flagd/README.md the minimal PHP version number is missing which is displayed on the flags.dev site, this likely has to be rebuilt or copied because the version number is present in the main documentation file (https://github.com/open-feature/php-sdk-contrib/blob/main/README.md)