remove obsolete explanation for NO_HZ
remove obsolete explanation for NO_HZ

stlankes/HermitCore,RWTH-OS/HermitCore,stlankes/HermitCore,stlankes/HermitCore,RWTH-OS/HermitCore,RWTH-OS/HermitCore,stlankes/HermitCore,RWTH-OS/HermitCore,stlankes/HermitCore,stlankes/HermitCore,RWTH-OS/HermitCore,RWTH-OS/HermitCore