Ashcan updates

Hey all! This one's a small update with a couple short patch notes. I was pretty happy with the Ashcan release, but I realized (thanks to some kind messages) that there were a couple inconsistencies from the original drafting process. I've clarified a few things: 

• How exploding dice work. This now reads a little bit clearer (I hope)
• Hazards. I removed an old piece of the draft that referenced "If a hazard has 3 or more dice remaining..." and replaced it with the updated "Any remaining hazard dice [have effect]
• Several small, line-level edits. 

That's it! Nothing world-shaking, just a few small clarifications.