title: How to add a fixed footer on all slides?
body: <p>I have a presentation set up with <code>reveal.js</code> which is meant to be used unattended. So, I want to be able to show a little footer (or another link somewhere) on all slides that points to an 'Information Slide' with data about the author, how to use the slides etc.</p>
  
  <p>(This is to aid people who don't really know how to use reveal.js as well as to show authorship information in detail.) </p>
  
  <p>I have not been able to find anything in the documentation and there does not seem to be a callback which I can utilize. </p>