Add link & insight from Mozilla's Connected Devices: Contributor Experience Research

[abbycabs]

Link: http://mzl.la/whyopensource

Not sure if there's a good place to link this, but I forgot about this excellent resource put together by the Participation team.

[ryanwarsaw]

This would probably fit well in one of the lessons under "Building Communities of Contributors", perhaps under "understand-meaningful-participation-and-distributed-leadership.md"?