fix(variables5): Add nudge for shadowing variable

exercises/variables/variables5.rs

@@ -6,6 +6,6 @@
 fn main() {
     let number = "T-H-R-E-E"; // don't change this line
     println!("Spell a Number : {}", number);
-    number = 3;
+    number = 3; // don't rename this variable
     println!("Number plus two is : {}", number + 2);
 }