Adding new specs

[bart-jaskulski]

Can you provide info (maybe included in readme) for contributors who'd like to add specs for another language?

ATM, I wanted to add spec for PHP, yet, despite creating spec file and appending it to defined language-specs in internal.fnl file I couldn't make it work.

Actually, I have no idea why it didn't work. Compiling with changes on another spec files were working, but adding a new one was impossible for me.