Fix wrong version

content/blog/2020-03-02-react-v16.13.0.md

@@ -101,7 +101,7 @@ class ClassParent extends React.Component {
 >
 > To see this warning, you need to have the [babel-plugin-transform-react-jsx-self](https://babeljs.io/docs/en/babel-plugin-transform-react-jsx-self) installed in your Babel plugins. It must _only_ be enabled in development mode. 
 > 
-> If you use Create React App or have the "react" preset with Babel 6+, you already have this plugin installed by default.
+> If you use Create React App or have the "react" preset with Babel 7+, you already have this plugin installed by default.
 
 ### Deprecating `React.createFactory` {#deprecating-reactcreatefactory}