Update index.rst Usage React with AssetMapper

src/React/doc/index.rst

@@ -99,6 +99,7 @@ Because the JSX format isn't pure JavaScript, using this library with AssetMappe
 requires some extra steps.
 
 .. note:: 
+
     Compile your ``.jsx`` files to pure JavaScript files. This can be done by
    installing Babel and the ``@babel/preset-react`` preset. Example:
    https://github.com/symfony/ux/blob/2.x/ux.symfony.com/package.json
@@ -156,6 +157,7 @@ Also, inside of your ``.jsx`` files, when importing another component, use the
     registerReactControllerComponents();
 
 .. note:: 
+
 Do not use **require.context** parameter. Not working with AssetMapper
 
 5- Finally, run the 'build' command below so that we can use the React components you wrote or installed.