v/vlib/builtin/README.md

## Description:

`builtin` is a module that is implicitly imported by every V program.
It implements the builtin V types `array`, `string`, `map`.
It also implements builtin functions like `println`, `eprintln`, `malloc`,
`panic`, `print_backtrace`.

The autogenerated documentation for builtin functions is lacking,
so for these functions, please refer to the
[official V documentation](https://github.com/vlang/v/blob/master/doc/docs.md).