Update math/power_of_two.cpp

Co-authored-by: David Leal <halfpacho@gmail.com>

math/power_of_two.cpp

@@ -22,6 +22,12 @@
  */
 
 #include <iostream>  /// for std::cout
+
+/**
+ * @namespace math
+ * @brief Mathematical algorithms
+ */
+namespace math {
 /**
  * @brief Function to test above algorithm
  * @param n description