Clearer installation steps

[mfbx9da4]

Hey this library looks really promising but the installation steps are not very clear and it's not clear how it is integrated into the example as this code

- (void)initializeInstrument
{
  facebook::react::CxxNativeModulePerfLogger logger = facebook::react::CxxNativeModulePerfLogger();
  facebook::react::BridgeNativeModulePerfLogger::enableLogging(std::make_unique<facebook::react::CxxNativeModulePerfLogger>(logger));
}

is never called in the example.

Also it would be great if it was on npm.