Docs: Improve documentation of known return types, plus other docs fixes.

See #48303


git-svn-id: https://develop.svn.wordpress.org/trunk@46660 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/ms-load.php

@@ -32,7 +32,7 @@ function is_subdomain_install() {
  * @access private
  * @since 3.1.0
  *
- * @return array Files to include.
+ * @return string[] Array of absolute paths to files to include.
  */
 function wp_get_active_network_plugins() {
 	$active_plugins = (array) get_site_option( 'active_sitewide_plugins', array() );