chore: added more descriptive TODOs

exercises/traits/traits1.rs

@@ -16,7 +16,7 @@ trait AppendBar {
 }
 
 impl AppendBar for String {
-    //Add your code here
+    // TODO: Implement `AppendBar` for type `String`.
 }
 
 fn main() {

exercises/traits/traits2.rs

@@ -17,7 +17,7 @@ trait AppendBar {
     fn append_bar(self) -> Self;
 }
 
-//TODO: Add your code here
+// TODO: Implement trait `AppendBar` for a vector of strings.
 
 #[cfg(test)]
 mod tests {