Document how args are passed from `wp_insert_site()` to `wp_initialize_site()`

[jeremyfelt]

The docs for wp_insert_site() include only the arguments that are used directly in that function. They should also mention how any other arguments passed along to the wp_initialize_site hook. By default, this can include user_id, title, options, and `meta.

[codemascot]

wp_insert_site() Documentation Update

[JeffPaul]

Per input in today's bugsrub, @jeremyfelt will look to wrap up work here this weekend.

[jeremyfelt]

In 45236:

Docs: Add arguments passed by wp_insert_site() to wp_initialize_site().

Props codemascot.
Fixes #45061.