Add part3

advanced/part3/README.md

@@ -0,0 +1,16 @@
+# Part 3
+
+To build everything, `cd` into this `part1/` directory and run:
+
+```shell
+elm make src/Main.elm --output=../server/public/elm.js
+```
+
+Then open [http://localhost:3000](http://localhost:3000) in your browser.
+
+## Exercise
+
+Resolve the TODOs in these files:
+* `src/Page/Home.elm`
+* `src/Page/Settings.elm`
+* `src/Page/Article.elm`