fix typo in README
fix typo in README

Change-Id: I78740c3ba41958038ac86599e761f4caec637fdf
Reviewed-on: http://review.couchbase.org/9233
Tested-by: Sergey Avseyev <87f6d5e4fd3644c3c20800cde7fd3ad1569370b3@gmail.com>
Reviewed-by: Matt Ingenthron <1fa2ef4755a9226cb9a0a4840bd89b158ac71391@couchbase.com>

dewolfe/couchbase-ruby-client,dewolfe/couchbase-ruby-client