add link to sunjay talk

src/traits/specialization.md

@@ -40,3 +40,9 @@ will use at trans time. Thus, we take special care to avoid projecting
 associated types unless either (1) the associated type does not use
 `default` and thus cannot be overridden or (2) all input types are
 known concretely.
+
+## Additional Resources
+
+[This talk][talk] by @sunjay may be useful.
+
+[talk]: https://www.youtube.com/watch?v=rZqS4bLPL24