message: add blog metrics to readme
diff: @@ -72,6 +72,8 @@ If you are coming from `react-native-sentry` which was our SDK `< 1.0` you shoul
  ## Blog posts
  +[Mobile Vitals - Four Metrics Every Mobile Developer Should Care About](https://blog.sentry.io/2021/08/23/mobile-vitals-four-metrics-every-mobile-developer-should-care-about/).
  +
  [Performance Monitoring Support for React Native](https://blog.sentry.io/2021/03/11/performance-monitoring-support-for-react-native/?utm_source=github&utm_medium=readme&utm_campaign=sentry-react-native).
  ## Resources
  