Add clarification comment on variable hoisting error in example

Author: Darkidd77

Sprint-1/2-mandatory-errors/2.js

@@ -3,3 +3,5 @@
 
 console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+
+// The error is that we are trying to use the variable cityOfBirth before it has been declared and assigned a value.