Link broken on jira docs, link to 'custom field types' on page extending.html is broken

Hi,

I noticed a bug on your website. On http://www.atlassian.com/software/jira/docs/latest/extending.html, selecting 'custom field types' (in the 'Custom Field Types' entry) results in a '500 Internal Server Error/More than 10 loops - erroring out.' using Opera and FireFox. IE only shows a 500.