The implementation of the `CSV` shortcut method is broken in Ruby 3
for calls that look like this:

```ruby
CSV(write_stream, col_sep: "|", headers: headers, write_headers: true) do |csv|
  ...
end
```

The above will result in the following error when the `CSV` method attempts to pass
on arguments to `CSV#instance`:

```
ArgumentError: wrong number of arguments (given 2, expected 0..1)
```

The issue is due to the changes in Ruby 3 relating to positional & keyword arguments.

This commit updates the `CSV()` shortcut implementation to work with Ruby 3, and also
updates the documentation for the shortcut method.

https://github.com/ruby/csv/commit/310dee45fa