Minor spacing update

Author: s10wen

react/README.md

@@ -421,13 +421,13 @@ This style guide is mostly based on the standards that are currently prevalent i
   Filter out unnecessary props when possible. Also, use [prop-types-exact](https://www.npmjs.com/package/prop-types-exact) to help prevent bugs.
 
   ```jsx
-  //good
+  // good
   render() {
     const { irrelevantProp, ...relevantProps  } = this.props;
     return <WrappedComponent {...relevantProps} />
   }
 
-  //bad
+  // bad
   render() {
     const { irrelevantProp, ...relevantProps  } = this.props;
     return <WrappedComponent {...this.props} />