Improve Documentation on Mixed-OS Clusters

Hello,

Currently our Documentation doesn't mention mixed-OS cluster deployments. In the Couchbase Server 3.x documentation, on the Supported Platforms page we indicate:

Important: Couchbase clusters on mixed platforms are not supported. Specifically, Couchbase Server on Mac OS X uses 64 vBuckets as opposed to the 1024 vBuckets used by other platforms. Due to this difference, if you need to move data between a Mac OS X cluster and a cluster hosted on another platform use `cbbackup` and `cbrestore`

After a customer asked if a cluster made up of Windows and Linux nodes, on the issue CBSE-6285 Engineering have clarified that such a deployment is not advised, and would not be supported by the Couchbase Engineering department.

Could we add something to the docs to indicate this? This information is missing, from what I can tell, from version 4.0 onwards, though it probably only needs to be added for 4.6 and onwards, perhaps 5.0 even.