Updated README to make it clear this is obsolete

Change-Id: I90624b88ad6a058b7d9f76ec9165c25f217fed22
Reviewed-on: http://review.couchbase.org/24187
Reviewed-by: Jens Alfke <jens@couchbase.com>
Tested-by: Jens Alfke <jens@couchbase.com>