Docs: Reformat the `orderby` section of `WP_Term_Query::__construct()` for better readability.

This makes it more consistent with the `fields` section.

See #49572.
Built from https://develop.svn.wordpress.org/trunk@47897


git-svn-id: https://core.svn.wordpress.org/trunk@47671 1a063a9b-81f0-0310-95a4-ce76da25c4cd