Sets the promote property of a node to 1.
$node: A node object.
$context: (optional) Array of additional information about what triggered the action. Not used for this action.
function node_promote_action($node, $context = array()) {
$node->promote = NODE_PROMOTED;
watchdog('action', 'Promoted @type %title to front page.', array(
'@type' => node_type_get_name($node),
'%title' => $node->title,
));
}