added comments to code blocks

Author: habibasorour

source/ch8_filehandling.ptx

@@ -12,7 +12,7 @@
         <program xml:id = "file-class-import-Python-example" interactive="activecode" language="python">
             <code>
             import math
-            print(math.sqrt(25))
+            print(math.sqrt(25)) # notice the lower case 'm' in math
             </code> 
         </program>
 
@@ -25,7 +25,7 @@
 
             public class SquareRoot {
                 public static void main(String[] args) {
-                    System.out.println(Math.sqrt(25));
+                    System.out.println(Math.sqrt(25)); // notice the upper case 'M' in Math
                 }
             }
             </code>