Clarifies when to use hyper-threading

Change-Id: I5f46e7a02a5e6c675a6c11c1126a34a563954b2e
O'Reilly Edit: Controller Node Clarification

This commit resolves the editor's comment regarding a "controller node"

Change-Id: Ib02def2fbafb4c71e248ddb0191c6a2e88cf2ae9
Merge "Clarifies when to use hyper-threading"
Merge "O'Reilly Edit: Controller Node Clarification"