Update symlink for details polyfill
Update symlink for details polyfill

This file has been moved, so these instructions are incorrect.

To test this:

In /govuk_elements_rails/vendor/assets

ls -l

`details.polyfill.js -> ../../../govuk_elements/assets/javascripts/govuk/details.polyfill.js`
ministryofjustice/govuk_elements_rails