Update documentation for PhantomJS
Update documentation for PhantomJS

We stopped installing this from S3 as of 705613c824c150ed363b43556a0b76b66154c850,
so this comment is incorrect.

alphagov/ci-puppet,alphagov/ci-puppet,boffbowsh/ci-puppet,alphagov/ci-puppet,boffbowsh/ci-puppet,boffbowsh/ci-puppet,alphagov/ci-puppet,boffbowsh/ci-puppet