fix: remove broken link for error handling

[aroyan]

Remove broken link in Performance Best Practices Using Express in Production on Handle exceptions properly section, there is a link point to Error Handling in Node.js but the page is not found now and I can't find a replacement for this so I think this is better to be removed

[dougwilson]

Great find! Looks like Joyent moved their aite around and here is the new url: https://www.tritondatacenter.com/node-js/production/design/errors

[aroyan]

Great find! Looks like Joyent moved their aite around and here is the new url: https://www.tritondatacenter.com/node-js/production/design/errors

Thank you, can't found them before. It's updated now