Ruby code sample improvement and MacOS Sonoma instructions

After trying to get ruby + couchbase working on my macos sonoma, there are 2 suggestions for improvements in the documentation:

1. On "Start Using the Ruby SDK", in the code sample, add a line to include Couchbase

require "couchbase"

include Couchbase # include Couchbase module for brevity 

This was needed for Cluster and ClusterOptions code to work.

2. For MacOS Sonoma, there is a bug with Cmake. Our forums has a solution but you need to dig through the details. Add following instructions (feel free to word this better):

For MacOS Sonoma users for Ruby sdk, the cmake 3.28.1 installed by homebrew is not able to build the couchbase gem whereas the same version (3.28.1) downloaded from https://github.com/Kitware/CMake/releases/download/v3.28.1/cmake-3.28.1-macos-universal.dmg 1 works.