Add a simple example for custom debugging helpers

The example found here is a bit complicated and incomplete.

I'd like to have an example for a simple class, for which I want to print a specific member.

For example:

class MyType
{
public:
  char value[50];
};

int main()
{
  MyType obj;
  strcpy(obj.value, "value");
  return 0;
}

How do I make the debugger print 'value' for MyType?

Another thing that confused me is that the doc says the qdump function should be inserted in gdbinit. For me, it didn't work. I needed to put it in an external file, and in gdbinit enter 'python execfile("/path/myfile.py")'. That's not clear enough (or maybe I did something wrong?)