Add detailed explanation for paddedPenceNumberString processing in 3-to-pounds.js

Author: moses77-boop

Sprint-2/3-mandatory-interpret/3-to-pounds.js

@@ -30,4 +30,8 @@ console.log(`£${pounds}.${pence}`);
 //    substring(0, length - 1): is a method that is invoked in the paragraph above to take every character in the string provided except the last one, leaving out the 'p'
 //    That is -> '399p' becomes '399'
 //    const penceStringWithoutTrailingP: used to store the value from 'penceString.substring(...)'
-  
+
+// 3. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+//    penceStringWithoutTrailingP is now '399'
+//    padStart(3, "0") is a method which guarantees that the numeric string is at least 3 characters long, and if it is shorter add '0' to the front until it is 3 characters long.
+//    padding to 3 ensures there is always at least one pounds digit and two pence digits.