lint fix

packages/next-mdx/readme.md

@@ -54,7 +54,6 @@ module.exports = withMDX({
 By default MDX will only match and compile MDX files with the `.mdx` extension.
 However, it can also be optionally configured to handle markdown files with the `.md` extension, as shown below:
 
-
 ```js
 // next.config.js
 const withMDX = require('@next/mdx')({
@@ -65,7 +64,6 @@ module.exports = withMDX()
 
 In addition, MDX can be customized with compiler options, see the [mdx documentation](https://mdxjs.com/packages/mdx/#compilefile-options) for details on supported options.
 
-
 ## Top level .mdx pages
 
 Define the `pageExtensions` option to have Next.js handle `.md` and `.mdx` files in the `pages` directory as pages: