Unified CPU Requirements (#1126)

Author: Rustin170506

src/building/prerequisites.md

@@ -47,7 +47,7 @@ These are not so much requirements as _recommendations_:
 
 * ~15GB of free disk space (~25GB or more if doing incremental builds).
 * \>= 8GB RAM
-* \>= 4 cores
+* \>= 2 cores
 * Internet access
 
 Beefier machines will lead to much faster builds. If your machine is not very