Add BombenProdukt/typeid for PHP to README.md

[faustbrian]

I've begun an implementation for PHP, which you can find at https://github.com/BombenProdukt/typeid. The encoding and decoding implementation is based on https://github.com/jetpack-io/typeid-js. At present, it passes all encodings as per https://github.com/jetpack-io/typeid/blob/main/spec/valid.yml. We are running the tests directly against the valid.yml and invalid.yml files to promptly detect any failures. Tests for the invalid.yml file are still missing, but I plan to add them in the coming days as time allows.

[loreto]

@faustbrian Thanks for contributing, having a PHP implementation would be great!

Due to a quirk of our internal setup, I need to accept the PR in our opensource monorepo and then it'll automatically get published here. Do you mind opening the PR there? The corresponding file is here: https://github.com/jetpack-io/opensource/blob/main/typeid/typeid/README.md

I'm also trying to keep the list of implementations in alphabetical order, so add PHP in-between Java and Python.

[faustbrian]

@loreto jetify-com/opensource#69