Additional README fixups

Fix bad path in cmake/unix example
Fix broken link for LCB doc page

Change-Id: I8ed71d5f3ca2d1fd5df3be19ed80abf9742d9e82
Reviewed-on: http://review.couchbase.org/43646
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>