Add Example for element/3

[jgarte]

https://www.scryer.pl/clpz.html#element/3

We should add a REPL example for element/3.

I can do this.

[jgarte]

:- use_module(clpz).

?- element(1, [0, 1, 2], 0).
%@    true.

?- element(1, [0, 1, 2], X).
%@    X = 0.

?- element(X, [0, 1, 2], 0).
%@    X = 1.

?- help(element/1).
%@    false.

[triska]

Please think about what a potential example should illustrate. Is there something in the documentation that can best be explained or illustrated by an example? Are there any remaining questions unless an example is added?

[jgarte]

Analogous to nth1/3.

I feel that this statement can be disambiguated. For example, How is element/3 comparable to nth1/3 exactly?

A code comparison example might be able to answer this question elegantly.

What do you think?