Update 01-debugging.pod6

Author: rafaelschipiura

doc/Programs/01-debugging.pod6

@@ -73,7 +73,7 @@ This can be handy as a cheap trace function.
 
 =head2 The C<Backtrace> class
 
-The C<Backtrace> class gets the current call stack, and can return it as a
+The L<Backtrace> class gets the current call stack, and can return it as a
 string:
 
     my $trace = Backtrace.new;