add I AM NOT DONE comments

exercises/generics/generics2.rs

@@ -1,5 +1,7 @@
 // This powerful wrapper provides the ability to store a positive integer value.
 // Rewrite it using generics so that it supports wrapping ANY type.
+
+// I AM NOT DONE
 struct Wrapper<u32> {
     value: u32
 }

exercises/generics/generics3.rs

@@ -6,6 +6,7 @@
 // Make the necessary code changes to support alphabetical report cards, thereby making the second
 // test pass.
 
+// I AM NOT DONE
 pub struct ReportCard {
     pub grade: f32,
     pub student_name: String,