Obsolete code in snowman left sidebar tutorial #150
Description
The code provided in the left sidebar tutorial for snowman (https://twinery.org/cookbook/sidebar_left/snowman/snowman_sidebar_left.html) is outdated and does not work in snowman 1.4.0 or snowman 2.0.2, thus not functioning at all in the most recent version of twine as snowman 1.3.0 is not a selectable option. Therefore this example should be updated to work with the modern versions of snowman available in twine.
In order to do this, the only changes needed would be replacing the two instances of #passage with tw-passage and the single instance of showpassage:after with sm.passage.shown