Bugfix in EADME.md: "Usage" had wrong heading size
Bugfix in EADME.md: "Usage" had wrong heading size

LLNL/llnl-hires-timers,LLNL/llnl-hires-timers,scalability-llnl/llnl-hires-timers,scalability-llnl/llnl-hires-timers