Update lisp doc and examples

[vinc]

No description provided.

[vinc]

> (define (or x y) (if x true (if y true false)))
or

> (or (= (/ 4 2) 2) (= (/ 4 0) 2))
Error: Division by zero

> (define-macro (or x y) `(if ,x true (if ,y true false)))
or

> (or (= (/ 4 2) 2) (= (/ 4 0) 2))
true

[vinc]

> (expand (let (x y) (1 2) (+ x y)))
((function (x y) (+ x y)) 1 2)

> (let (x y) (1 2) (+ x y))
3