Fix for WebPack users for accordion

the 28th of June, 2018

Fix for WebPack users for accordion

In fact, the listeners were not attached properly, and it was creating an issue with WebPack when loading the script.

This fix has been published on Github/NPM today (See Github repositery of Van11y accordion script). Documentation of the accessible accordion has also been updated.

A big thank to @Spone for the fix!