Fix JSX props log for Greeting (#802)

public/a-chain-reaction/index.md

···
 ```js
 const originalJSX = <Greeting person={alice} />;
 console.log(originalJSX.type);  // Greeting
-console.log(originalJSX.props); // { firstName: 'Alice', birthYear: 1970 }
+console.log(originalJSX.props); // { person: { firstName: 'Alice', birthYear: 1970 } }
 ```
 
 Under the hood, JSX constructs an object with the `type` property corresponding to the tag, and the `props` property corresponding to the JSX attributes.
···
 ```js {5-7}
 const originalJSX = <Greeting person={alice} />;
 console.log(originalJSX.type);  // Greeting
-console.log(originalJSX.props); // { firstName: 'Alice', birthYear: 1970 }
+console.log(originalJSX.props); // { person: { firstName: 'Alice', birthYear: 1970 } }
 
 const browserJSX = translateForBrowser(originalJSX);
 console.log(browserJSX.type);  // 'p'