Add rel='noopener noreferer' to external link

[kritsii]

This PR adds rel="noopener noreferrer" to links that use target="_blank".
This improves security by preventing reverse tabnabbing and follows HTML best practices.

[lb-]

It may be simpler to se this on the root head tag, inside a meta element.

This way it doesn't need to be set on each link individually.

https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Referrer-Policy#integration_with_html

[kritsii]

Thanks for the suggestion!
Just to clarify are you suggesting setting a global policy (for example via tag) instead of adding rel = "noopener noreferrer" on individual links? Happy to update implementation accordingly.