Update Kotlin example in user manual for new 1.2 syntax

[remkop]

Update link in picocli user manual: http://picocli.info/#_kotlin

Kotlin 1.2 (released Nov 28, 2017) officially supports Array literals in annotations:
http://kotlinlang.org/docs/reference/whatsnew12.html#array-literals-in-annotations

TODO: check if the array literals are needed for single-element literals

// Kotlin 1.2+:
@AnnWithArrayMethod(names = ["abc", "foo", "bar"]) 
class C {}

// Older Kotlin versions:
@AnnWithArrayMethod(names = arrayOf("abc", "foo", "bar")) 
class D {}

// TODO is this possible in Kotlin 1.2?
@AnnWithArrayMethod(names = "abc") 
class E {}