add examples for eachk

[rwtolbert]

add examples for eachk

[sogaiu]

May be using [:a :b :c :d :e] as below instead of [1 2 3 4 5] still provides enough "surprise" and is slightly less confusing?

# prints 0 1 2 3 4
(eachk i [:a :b :c :d :e] (prin i " ")) # -> nil

Above, I tried to work in a bit of the content of our discussion on Zulip as well.

[sogaiu]

LGTM