Update README.md to include link to talk
Adds link to Recurse Center talk:
Closes
@@ -29,6 +29,8 @@ Goals include:
* ***Developer friendliness***. It should be easy to customize xi editor, whether
by adding plug-ins or hacking on the core.
+**Learn more** in the Recurse Center talk covering Xi: https://www.recurse.com/events/localhost-raph-levien
+
Screenshot (will need to be updated as syntax coloring and UI polish is added):
![xi-mac screenshot](/docs/docs/img/xi-mac-screenshot.png?raw=true)
