title: .flowconfig file in react-native project is missing
body: <p>I do not have <code>.flowconfig</code> file in my react-native project.<br>
  Even then if I add flow locally as :</p>
  
  <pre><code>yarn add --dev flow-bin babel-preset-flow
  </code></pre>
  
  <p>and then do flow init, it creates an empty <code>.flowconfig</code> file with the latest flow version displayed at end of the file as 0.79.1 . Is it fine? and the rules I had to copy from <a href="https://github.com/facebook/react-native/blob/master/.flowconfig" rel="nofollow noreferrer">https://github.com/facebook/react-native/blob/master/.flowconfig</a> which is regularly updated with current flow version(now 0.79.1).</p>
  
  <pre><code>React Native Environment Info:
      System:
        OS: macOS High Sierra 10.13.4
        CPU: x64 Intel(R) Core(TM) i7-4770HQ CPU @ 2.20GHz
        Memory: 4.56 GB / 16.00 GB
        Shell: 3.2.57 - /bin/bash
      Binaries:
        Node: 8.11.3 - /usr/local/bin/node
        Yarn: 1.1.0 - /usr/local/bin/yarn
        npm: 5.6.0 - /usr/local/bin/npm
        Watchman: 4.9.0 - /usr/local/bin/watchman
      SDKs:
        iOS SDK:
          Platforms: iOS 12.0, macOS 10.14, tvOS 12.0, watchOS 5.0
      IDEs:
        Android Studio: 3.0 AI-171.4443003
        Xcode: 10.0/10L232m - /usr/bin/xcodebuild
      npmPackages:
        react: 16.4.1 =&gt; 16.4.1
        react-native: 0.56.0 =&gt; 0.56.0
      npmGlobalPackages:
        create-react-native-app: 1.0.0
        react-native-cli: 2.0.1
        react-native-git-upgrade: 0.2.7
  Editor: VSCode
  </code></pre>
  
  <p>Or
  should I not use flow at all in the project, cause may be new version of <code>react-native</code> takes care of it?</p>