Docs: Improve documentation for `get_page_by_title()`.

Props atachibana.
Fixes #47860.

git-svn-id: https://develop.svn.wordpress.org/trunk@45779 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/post.php

@@ -4881,11 +4881,19 @@ function get_page_by_path( $page_path, $output = OBJECT, $post_type = 'page' ) {
 /**
  * Retrieve a page given its title.
  *
+ * If more than one post uses the same title, the post with the smallest ID will be returned.
+ * Be careful: in case of more than one post having the same title, it will check the oldest
+ * publication date, not the smallest ID.
+ *
+ * Because this function uses the MySQL '=' comparison, $page_title will usually be matched
+ * as case-insensitive with default collation.
+ *
  * @since 2.1.0
+ * @since 3.0.0 The `$post_type` parameter was added.
  *
  * @global wpdb $wpdb WordPress database abstraction object.
  *
- * @param string       $page_title Page title
+ * @param string       $page_title Page title.
  * @param string       $output     Optional. The required return type. One of OBJECT, ARRAY_A, or ARRAY_N, which correspond to
  *                                 a WP_Post object, an associative array, or a numeric array, respectively. Default OBJECT.
  * @param string|array $post_type  Optional. Post type or array of post types. Default 'page'.