Update "Test Metadata" documentation to include PHP


#1

It seems that https://circleci.com/docs/test-metadata is missing PHP.

PHPUnit can generate junit xml files as an option via "–log-junit ". See documentation here: https://phpunit.de/manual/current/en/textui.html


#2

Docs have been updated, thank you very much for sharing! :sunglasses:


#3