Merge pull request #5547 from kenjis/fix-docs-cookie_helper.rst

docs: fix variable name in get_cookie()

user_guide_src/source/helpers/cookie_helper.rst

@@ -42,7 +42,7 @@ The following functions are available:
 .. php:function:: get_cookie($index[, $xssClean = false])
 
  :param string $index: Cookie name
- :param bool $xss_clean: Whether to apply XSS filtering to the returned value
+ :param bool $xssClean: Whether to apply XSS filtering to the returned value
  :returns: The cookie value or null if not found
  :rtype: mixed