Create redirects for cert-manager annotations.

It would be great if https://cert-manager.io/renew-before redirected to: https://cert-manager.io/docs/reference/api-docs/#cert-manager.io/v1.CertificateSpec/renewBefore - a proprer deep link is dependent on https://github.com/ahmetb/gen-crd-api-reference-docs/issues/120 I'm told that this is managed by: https://github.com/cert-manager/website/blob/master/public/_redirects