chore: tidied up unmatched backticks

exercises/traits/traits1.rs

@@ -2,7 +2,7 @@
 // Time to implement some traits!
 //
 // Your task is to implement the trait
-// `AppendBar' for the type `String'.
+// `AppendBar` for the type `String`.
 //
 // The trait AppendBar has only one function,
 // which appends "Bar" to any object

exercises/traits/traits2.rs

@@ -1,7 +1,7 @@
 // traits2.rs
 //
 // Your task is to implement the trait
-// `AppendBar' for a vector of strings.
+// `AppendBar` for a vector of strings.
 //
 // To implement this trait, consider for
 // a moment what it means to 'append "Bar"'