[plt-scheme] Where is the source for the PLT Mzscheme Language Manual?

I'm embarrassed to say I haven't been able to answer that question for
myself.  It doesn't appear to be part of the source in CVS
(:pserver:anonymous at anoncvs.plt-scheme.org:/cvs), and I haven't
figured it out from looking at the web.

I wanted to make a tiny change or two to some text, then post it here
for as a suggested patch.
-- 
Because he pays close attention, a Navy pilot can land a
40,000 lb. aircraft at 140 miles per hour on a pitching carrier
deck, at night, more safely than the average teenager can cut a
bagel.
        -- Paul Graham