message: Adding default locale as `en`. Addresses
diff: @@ -13,7 +13,7 @@ class Doc extends React.Component {
  className="edit-page-link button"
  href={
  'https://github.com/facebook/jest/edit/master/docs/' +
  - this.props.language +
  + (this.props.language || 'en') +
  '/' +
  this.props.source
  }
  