Should update C SDK 2.10 docs to explain libcouchbase@2

Due to how homebrew handles major version upgrades, installing libcouchbase via homebrew now requires the use of libcouchbase@2, this also installs it as keg-only and it does not get symlinked on the system by default. Instructions on how to make this work correctly, and how people previously using "libcouchbase" can upgrade to using "libcouchbase@2" should be added somewhere in the docs.