Update 02_advanced_stack_usage.ipynb

[gdsoumya]

Fixed typo it should be CDR instead of CAR which removes the left part of the PAIR from stack

[claudebarde]

I am not sure that's a typo. It means that CDR extracts the right part of a pair as CAR extracts the left part.
If the wording seems confusing to you, would you like to offer a suggestion?

[gdsoumya]

@claudebarde quoting from the documentation :

The first one is CAR that takes a pair at the top of the stack and returns the value on the left side. Note that the value on the right is taken out of the stack and lost:

and then

To extract the right part of the element on top of the stack, you can use CDR. As for CAR, the left part of the pair will be removed from the stack and lost:

While reading the tutorial if feels the first statement says CAR removes the right part permanently and the second says CAR removes the left part permanently. Making the second statement as CDR seems to make sense.