I hope this still helps. The typo does not effect the specification of
the feature, so it isn't very harmful.
In the third paragraph of section "Informal specification", (list 'a #;
#;'b 'c 'd) is said to read as (list (quote x) (quote d)). The 'a turned
to an 'x. The typo appears in lines 86-87 in the official HTML version.