WordPress.dev: Rename to WordPressorg.dev

There are 3 second-level 'wordpress' domains, and WordPress.tv and WordPress.net are using WordPressTV.dev and WordPressnet.dev, respectively, so this makes wordpressorg.dev consistent.

It also avoids the potential for conflicts with VVV and other custom sites that could use 'wordpress.dev' to refer to Core rather than WordPress.org.