[readme] Add note about commented out tests

README.md

@@ -16,7 +16,7 @@ usually marked with `???`.
 | 3: Error Handling               | [`errors`](src/main/scala/errors)                                 | `testOnly errors.*`
 | 4: Laziness                     | [`laziness`](src/main/scala/laziness/)                            | `testOnly laziness.*`
 | 5: Algebras, Laws, and Monoids  | [`algebra`](src/main/scala/algebra/)                              | `testOnly algebra.*`
-| 6: Typeclasses                  | [`typeclasses`](src/main/scala/typeclasses/)                      | `testOnly typeclasses.*`
+| 6: Typeclasses                  | [`typeclasses`](src/main/scala/typeclasses/)                      | `testOnly typeclasses.*` (needs some uncommenting)
 
 ## Usage tips:
 To keep your local solutions to the exercises when pulling from the repository,