add slides path to publishing root for speaker notes
add slides path to publishing root for speaker notes

RevealJS speaker notes loads the url that RevealJS is running on in an
iframe and adds a query string to it.

this was resulting in a url like publishing-root/?param-list, which
caused the speaker notes to not load previews properly.

using publishing-root/index.html fixes the problem

jacksingleton/hacker-slides,jacksingleton/hacker-slides,jacksingleton/hacker-slides,jacksingleton/hacker-slides,jacksingleton/hacker-slides