Added guide for setting up Next.js with MDX

docs/advanced-features/using-mdx.md

@@ -0,0 +1,183 @@
+---
+description: Learn how to use @next/mdx in your Next.js project.
+---
+
+# Using MDX with Next.js
+
+MDX is a superset of markdown that lets you write JSX directly in your markdown files. It is a powerful way to add dynamic interactivity, and embed components within your content, helping you to bring your pages to life.
+
+Next.js supports MDX through a number of different means, this page will outline some of the ways you can begin integrating MDX into your Next.js project.
+
+## Why use MDX?
+
+Authoring in markdown is an intuitive way to write content, its terse syntax, once adopted, can enable you to write content that is both readable and maintainable. Because you can use `HTML` elements in your markdown, you can also get creative when styling your markdown pages.
+
+However, because markdown is essentially static content, you can't create _dynamic_ content based on user interactivity. Where MDX shines is in its ability to let you create and use your React components directly in the markup. This opens up a wide range of possibilities when composing your sites pages with interactivity in mind.
+
+## MDX Plugins
+
+Internally MDX uses remark and rehype. Remark is a markdown processor powered by a plugins ecosystem. This plugin ecosystem lets you parse code, transform `HTML` elements, change syntax, extract frontmatter, and more.
+
+Rehype is an `HTML` processor, also powered by a plugin ecosystem. Similar to remark, these plugins let you manipulate, sanitize, compile and configure all types of data, elements and content.
+
+To use a plugin from either remark or rehype, you will need to add it to the MDX packages config.
+
+## `@next/mdx`
+
+The `@next/mdx` package is configured in the `next.config.js` file at your projects root. **It sources data from local files**, allowing you to create pages with a `.mdx` extension, directly in your `/pages` directory.
+
+### Setup `@next/mdx` in Next.js
+
+The following steps outline how to setup `@next/mdx` in your Next.js project:
+
+1. Install the required packages:
+
+   ```terminal
+     npm install @next/mdx @mdx-js/loader
+   ```
+
+2. Require the package and configure to support top level `.mdx` pages. The following adds the `options` object key allowing you to pass in any plugins:
+
+   ```js
+   // next.config.js
+
+   const withMDX = require('@next/mdx')({
+     extension: /\.mdx?$/,
+     options: {
+       remarkPlugins: [],
+       rehypePlugins: [],
+     },
+   })
+   module.exports = withMDX({
+     pageExtensions: ['js', 'jsx', 'md', 'mdx'],
+   })
+   ```
+
+3. Create a new MDX page within the `/pages` directory:
+
+   ```bash
+     - /pages
+       - my-mdx-page.mdx
+     - package.json
+   ```
+
+## Using Components, Layouts and Custom Elements
+
+You can now import a React component directly inside your MDX page. Note that `@next/mdx` does **not** support frontmatter (frontmatter is a YAML like key/value pairing that can be used to store data about a page), instead, you can export data from within the `.mdx` file:
+
+```md
+import { MyComponent } from 'my-components'
+
+export const meta = {
+author: 'Rich Haines'
+}
+
+# My MDX page
+
+This is a list in markdown:
+
+- One
+- Two
+- Three
+
+Checkout my React component:
+
+<MyComponent/>
+```
+
+### Layouts
+
+To add a layout to your MDX page, create a new component and import it into the MDX page. Then you can wrap the MDx page with your layout component:
+
+```md
+import { MyComponent, MyLayoutComponent } from 'my-components'
+
+export const meta = {
+author: 'Rich Haines'
+}
+
+# My MDX Page with a Layout
+
+This is a list in markdown:
+
+- One
+- Two
+- Three
+
+Checkout my React component:
+
+<MyComponent/>
+
+export default = ({ children }) => <MyLayoutComponent meta={meta}>{children}</MyLayoutComponent>
+```
+
+### Custom Elements
+
+One of the pleasant aspects of using markdown, is that it maps to native `HTML` elements, making writing fast, and intuitive:
+
+```md
+# H1 heading
+
+## H2 heading
+
+This is a list in markdown:
+
+- One
+- Two
+- Three
+```
+
+The above generates the following `HTML`:
+
+```html
+<h1 id="h1-heading">H1 heading</h1>
+
+<h2 id="h2-heading">H2 heading</h2>
+
+<p>This is a list in markdown:</p>
+
+<ul>
+  <li>One</li>
+  <li>Two</li>
+  <li>Three</li>
+</ul>
+```
+
+When you want to style your own elements to give a custom feel to your website or application, you can pass in shortcodes. These are your own custom components that map to `HTML` elements. To do this you use the `MDXProvider` and pass a components object as a prop. Each object key in the components object maps to a `HTML` element name.
+
+```jsx
+// pages/index.js
+
+import { MDXProvider } from '@mdx-js/react'
+import Image from 'next/image'
+import { Heading, Text, Pre, Code, Table } from 'my-components'
+
+const ResponsiveImage = (props) => (
+  <Image alt={props.alt} layout="responsive" {...props} />
+)
+
+const components = {
+  img: ResponsiveImage,
+  h1: Heading.H1,
+  h2: Heading.H2,
+  p: Text,
+  code: Pre,
+  inlineCode: Code,
+}
+
+export default function Post(props) {
+  return (
+    <MDXProvider components={components}>
+      <main {...props} />
+    </MDXProvider>
+  )
+}
+```
+
+## Helpful Links
+
+- [MDX](https://mdxjs.com)
+- [`@next/mdx`](https://www.npmjs.com/package/@next/mdx)
+- [remark](https://github.com/remarkjs/remark)
+- [rehype](https://github.com/rehypejs/rehype)
+- [gray-matter: Adding frontmatter to your MDX file](https://github.com/jonschlinkert/gray-matter)

docs/manifest.json

@@ -148,6 +148,10 @@
               "title": "Absolute Imports and Module Path Aliases",
               "path": "/docs/advanced-features/module-path-aliases.md"
             },
+            {
+              "title": "Using MDX",
+              "path": "/docs/advanced-features/using-mdx.md"
+            },
             {
               "title": "AMP Support",
               "routes": [