An image for search-engines/facebook

This should close #297? Please let me know what you all think of the image, tag-line, code, etc.
cc. @roryaronson @simonv3 @rickcarlino @emily-plummer and everyone else
Alright, swapped! I'm not sure how to test this locally, so give it a once over to see if it looks right and then we can test on staging.