docs: fix example code not printing properly

[lq259]

This code example:

fn foo() (int, int) {
return 2, 3
}

fn main() {
c, _ := foo()
print(c)
// no warning about unused variable returned by foo.
}

is supposed to print out the second returned variable from foo(), which is 3.

The issue is that it uses print() instead of println() to do so, resulting in nothing being printed to output, because a new line has not been started.
There are multiple ways to start a new line for this context, println() is easiest.