The version 1.3.0 of Snowman that comes pre-installed with the Twine 2.x application is the story format you linked to.
It is a little confusing but the 2 mentioned in that project's name (Snowman-2) is referring to which Twine application (1.x or 2.x) it is compatible with, and not the version of the story format itself. There is a companion project named Snowman-1.4 which is compatible with the Twine 1.x application.