I do think the semicolon behavior is a bit confusing. The documentation explains that expressions aren't auto-returned if they're followed by a semicolon, but I don't think that quite covers the behavior I pointed out. I might be missing something else from the documentation, though...
Also, I found one more major issue. Your documentation uses the numeric literal "3.1415" in the explanation for named parameters. That really needs to be "3.1416". :P