Fix typo in url_title function description.
diff --git a/system/helpers/url_helper.php b/system/helpers/url_helper.php
index 5f8c6ce..6a033d6 100644
--- a/system/helpers/url_helper.php
+++ b/system/helpers/url_helper.php
@@ -474,7 +474,7 @@
* @param string $str Input string
* @param string $separator Word separator
* (usually '-' or '_')
- * @param bool $lowercase Wether to transform the output string to lowercase
+ * @param bool $lowercase Whether to transform the output string to lowercase
* @return string
*/
function url_title($str, $separator = '-', $lowercase = FALSE)