Kernel compiling: talking about CPU cores or threads

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>

slides/sysdev-kernel-building/sysdev-kernel-building.tex

@@ -395,7 +395,7 @@ \subsection{Compiling and installing the kernel}
   \begin{itemize}
     \item Run it in the main kernel source directory!
     \item Remember to run multiple jobs in parallel
-          if you have multiple CPU cores. Our advice:
+          if you have multiple CPU cores / threads. Our advice:
           \code{ncpus * 2} or \code{ncpus + 2}, to fully load
           the CPU and I/Os at all times.\\
           Example: \code{make -j 8}