Shift everything forward a partg

part4/README.md

@@ -1,4 +1,4 @@
-Part 4
+Part 3
 ======
 
 The instructor will paste notes from the lesson, including code examples from
@@ -21,4 +21,5 @@ elm-live Main.elm --open --output=elm.js
 
 ## References
 
-* [Union Types syntax reference](http://elm-lang.org/docs/syntax#union-types)
+* [`onClick` documentation](http://package.elm-lang.org/packages/evancz/elm-html/4.0.2/Html-Events#onClick)
+* [record update syntax reference](http://elm-lang.org/docs/syntax#records) (e.g. `{ model | query = "foo" }`)