fix whitespace

Author: fsaadatmand

chapter03/3-6.c

@@ -2,6 +2,7 @@
  * Exercise 3-6. Write a version of itoa that accepts three arguments instead
  * of two. The third argument is a minimum field width; the converted number
  * must be padded with blanks on the left if necessary to make it wide enough.
+ *
  * By Faisal Saadatmand
 */