Tiny post-jam bugfix update

Super tiny bugfix update.

• Since a complaint pretty much everyone playing this game in the jam had was that it's too hard to figure out what all the block types' quirks are, I've added a help screen to the title screen that points it out. Press F1 on the title screen to view this. (I also added a screenshot of this help screen if you don't want to re-download the game just for that)
• I also changed the instructional text font from a futuristic space font to a book-style serif font since I felt this matches the game's victorian-era style a bit better.
• Since the jam is over, I've enabled donations on the game page. The game will remain free, though, no worries!