Added @link to CakeNumber's docblock

lib/Cake/Utility/CakeNumber.php

@@ -135,6 +135,7 @@ public static function toReadableSize($size) {
  * @param mixed $default Value to be returned when invalid size was used, for example 'Unknown type'
  * @return mixed Number of bytes as integer on success, `$default` on failure if not false
  * @throws CakeException On invalid Unit type.
+ * @link http://book.cakephp.org/2.0/en/core-libraries/helpers/number.html#NumberHelper::fromReadableSize
  */
 	public static function fromReadableSize($size, $default = false) {
 		if (ctype_digit($size)) {
@@ -246,6 +247,7 @@ public static function format($value, $options = false) {
  * @param float $value A floating point number
  * @param array $options
  * @return string formatted delta
+ * @link http://book.cakephp.org/2.0/en/core-libraries/helpers/number.html#NumberHelper::formatDelta
  */
 	public static function formatDelta($value, $options = array()) {
 		$places = isset($options['places']) ? $options['places'] : 0;
@@ -404,6 +406,7 @@ public static function addFormat($formatName, $options) {
  *
  * @param string $currency Default currency string used by currency() if $currency argument is not provided
  * @return string Currency
+ * @link http://book.cakephp.org/2.0/en/core-libraries/helpers/number.html#NumberHelper::defaultCurrency
  */
 	public static function defaultCurrency($currency = null) {
 		if ($currency) {