Improve menu.inc documentation for menu_tree_collect_node_links() and menu_tree_check_access()

I improved the documentation for menu_tree_collect_node_links() and menu_tree_check_access():

/**
 * Recursive helper function - collect node links.
 *
 * @param $tree
 *   The menu tree you wish to collect node links from.
 * @param $node_links
 *   An array in which to store the collected node links.
 */
function menu_tree_collect_node_links(&$tree, &$node_links) {

/**
 * Check access and perform other dynamic operations for each link in the tree.
 *
 * @param $tree
 *   The menu tree you wish to operate on.
 * @param $node_links
 *   A collection of node link references generated from $tree by
 *   menu_tree_collect_node_links().
 */
function menu_tree_check_access(&$tree, $node_links = array()) {