Fix parameter typo in comment in Multihop Swaps doc

[paul-leydier]

Hi everyone, I think there might be a typo in the Multihop Swaps - Calling the function example.

        // The format for pool encoding is (tokenIn, fee, tokenOut/tokenIn, fee, tokenOut) where tokenIn/tokenOut parameter is the shared token across the pools.

If I'm not mistaken, tokenIn/tokenOut should be replaced by tokenOut/tokenIn to be coherent with the early part of the comment.