Added a line to include the presentation url within the youtube description…

Merged Dimitrie Hoekstra requested to merge add-presentation-urls-to-youtube into master

It states that you should make the presentation viewable by anyone with the link (view-only).

This is important as a lot of links are shared within those presentations, which are really useful for people to dive into certain topics. It's nice in general to have access to the presentation (especially as we make it a big deal to include the presentation URL's in each calendar appointment for ourselves)