Docs: Improve the `$post_type` parameter description in the DocBlock for `register_post_type()`.

See #32246.

Built from https://develop.svn.wordpress.org/trunk@37884


git-svn-id: http://core.svn.wordpress.org/trunk@37825 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/post.php

@@ -897,13 +897,16 @@ function get_post_types( $args = array(), $output = 'names', $operator = 'and' )
  *
  * @since 2.9.0
  * @since 3.0.0 The `show_ui` argument is now enforced on the new post screen.
- * @since 4.4.0 The `show_ui` argument is now enforced on the post type listing screen and post editing screen.
+ * @since 4.4.0 The `show_ui` argument is now enforced on the post type listing
+ *              screen and post editing screen.
  *
  * @global array      $wp_post_types List of post types.
  * @global WP_Rewrite $wp_rewrite    Used for default feeds.
  * @global WP         $wp            Used to add query vars.
  *
- * @param string $post_type Post type key, must not exceed 20 characters.
+ * @param string $post_type Post type key. Must not exceed 20 characters and may
+ *                          only contain lowercase alphanumeric characters, dashes,
+ *                          and underscores. See sanitize_key().
  * @param array|string $args {
  *     Array or string of arguments for registering a post type.
  *

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.6-alpha-37883';
+$wp_version = '4.6-alpha-37884';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.