Current path in developer subdomain should redirect to current docs

Old style URLs in the developer subdomain with current in the path are redirecting to the Couchbase Server 6.0 documentation. They should redirect to the current Couchbase Server documentation.

For example,

https://developer.couchbase.com/documentation/server/current/n1ql/n1ql-language-reference/let.html

should redirect to

https://docs.couchbase.com/server/current/n1ql/n1ql-language-reference/let.html