Update documentation for is_new_day().

props obenland.
fixes #28333.

git-svn-id: https://develop.svn.wordpress.org/trunk@28588 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/functions.php

@@ -605,11 +605,12 @@ function wp_get_http_headers( $url, $deprecated = false ) {
 }
 
 /**
- * Whether today is a new day.
+ * Whether the publish date of the current post in the loop is different from the
+ * publish date of the previous post in the loop.
  *
  * @since 0.71
- * @uses $day Today
- * @uses $previousday Previous day
+ * @global string $currentday The day of the current post in the loop.
+ * @global string $previousday The day of the previous post in the loop.
  *
  * @return int 1 when new day, 0 if not a new day.
  */