Add set up instructions

Author: pomber

readme.md

@@ -7,3 +7,30 @@ Build first-class code walkthroughs for the web. Whether you are writing blog po
 
 There are no docs yet, but you can [explore the demos](https://codehike.org/#demos) for an overview of all the features and how to use them.
 
+## How to set up Code Hike
+
+1. First you need MDX v2 (or [xdm](https://github.com/wooorm/xdm/)). See [MDX v2 docs](https://mdxjs.com/docs/getting-started/) on how to set it up.
+2. Install Code Hike remark plugin with `yarn add @code-hike/mdx@next`
+3. Add the remark plugin to the MDX loader options. This depends on the bundler or site generator you are using. It usually looks something like this:
+
+```js
+const { remarkCodeHike } = require("@code-hike/mdx");
+const theme = require("shiki/themes/monokai.json"); // any theme from shiki
+
+// ...
+// somewhere on your bundler configuration:
+//      {
+//        loader: "@mdx-js/loader",
+//        options: {
+            remarkPlugins: [[remarkCodeHike, { theme }]],
+//        },
+//      },
+// ...
+```
+4. Add Code Hike's CSS. Also depends on your stack. Usually you can _just_ import it:
+
+```js
+import "@code-hike/mdx/dist/index.css";
+```
+
+5. Create an mdx file and copy the code from any of the [demos](https://codehike.org/#demos) to see if it works