[Documentation] Identify testware defects vs defects in the product

A disclaimer on test-ware defects vs defects in the project and how to identify them.

(Perhaps document any  known test-ware defects and express that virtual machines are given low resources which may cause certain nemesis processes to crash e.g. due to compaction and rebalancing). 

Furthermore, if a defect in the project is identified: how to file a bug report and what data is required.

Should also express that we’re aiming to be sequential consistent and non linearisable under specific durability requirements and how to configure them via the flags passed to the testing framework.

Explain that there me be linearizability failures, but we aim to pass when using the seqchecker.