I'm happy to hear you've been enjoying it so far!
The number is a bit of a sham, the major (0) stands for incomplete, but it started out as 0.8.x to make it easy to remember that was the release for chapter 8. So 0.9.x is for the current chapter 9, and then we'll have 0.10.x for chapter 10, and then it's either 0.11 for chapter 11 with 1.0 for the epilogue, or we'll have 1.0 for chapter 11+ epilogue, depending whether if I release those separately or together.