Added option to Untie boat inside walk

The option to untie the boat inside the /create-your-own-adventure/english/explore-outside/journey-to-flaming-tower/walk/ directory has been added.

I don't really understand the logic behind this link.  It takes you to a page that starts off "You wave goodbye to the marshmallow structure", but you left the marshmallow structure a while ago in this path.  Also, I would have guessed "Try other methods" to mean other methods of getting the boat.  If you meant this option to be ignoring the boat, I would make that a little more clear.