Avoid neologism

(that isn't quite what we mean here anyway)

doc/Language/testing.pod6

@@ -219,7 +219,7 @@ given expression, and produce standardized test output accordingly.
 In practice, the expression will often be a call to a function or method that
 you want to unit-test.
 
-=head2 By truthiness
+=head2 By C<Bool> value
 
 =item X<ok($value, $description?), nok($condition, $description?)|ok,nok>