Website: update docs (intro & install)

Author: MoOx

website/docs/index.md

@@ -49,6 +49,18 @@ introduce an additional cost. The JavaScript code produced by BuckleScript will
 directly hit React & React Native JavaScript implementation, without any extra
 runtime & bundle cost.
 
+## Using Reason & Reason React
+
+_Reason React Native_ is a package that works with
+[Reason](https://reasonml.github.io/) & use
+[Reason React](https://reasonml.github.io/reason-react/). For this reasons (!),
+if you are unfamiliar on of this two, we encourage you to have a look to their
+documentations as soon as you don't find an answer you might have here.
+
+And one day or another, you will also have to look for answers on
+[BuckleScript](https://bucklescript.github.io/docs/en/what-why), our
+Reason-to-JavaScript compiler.
+
 ---
 
 ## Further reading

website/docs/install.md

@@ -3,7 +3,113 @@ id: install
 title: Installation
 ---
 
-@todo
+Depending on how you want to start with _Reason React Native_, you have
+different options to install it:
+
+- [Create a new project with _Reason React Native_](#create-a-new-project-with-reason-react-native)
+- [Add _Reason React Native_ to an existing project](#add-reason-react-native-to-an-existing-project)
+- [Migrating from `bs-react-native` to _Reason React Native_](/reason-react-native/en/docs/migration/jsx3/)
+
+All options will basically help you to have :
+
+- [BuckleScript](https://bucklescript.github.io/) (`bs-platform` - includes
+ [ReasonML](https://reasonml.github.io)!)
+- [Reason React](https://reasonml.github.io/reason-react/) (`reason-react`)
+- _Reason React Native_ (`reason-react-native`)
+
+Below we assume you are already familiar with React Native. If you are new to
+React Native, please have a quick look to
+[React Native Getting Started documentation](https://facebook.github.io/react-native/docs/getting-started.html)
+in order to get the minimal requirements.
+
+## Create a new project with _Reason React Native_
+
+React Native allows to create new project from a template, so we made one. By
+choosing this option you will get an hello world project that will already have
+all the requirements included.
+
+```console
+react-native init MyApp --template reason
+```
+
+💖 Now that you project is setup, you can just check
+[how to use _Reason React Native_](#using-reason-react-native) right away!
+
+---
+
+⚠️ We don't provide yet instructions for _Expo_ users. _If you are familiar with
+Expo, feel free to open
+[an issue](https://github.com/reasonml-community/reason-react-native/issues/new?title=Expo+template)
+so we can discuss about that_.
+
+## Add _Reason React Native_ to an existing project
+
+If you already have an existing project, it's really fast to get all the thing
+you need to start using Reason React Native right away!
+
+Got into your project root & then install the requirements
+
+```console
+yarn add bs-platform --dev
+yarn add reason-react reason-react-native
+```
+
+Then create a file named `bsconfig.json` at the same level at your
+`package.json` with the following content
+
+```json
+{
+ "name": "my-reason-react-native-app",
+ "refmt": 3,
+ "reason": {
+ "react-jsx": 3
+ },
+ "package-specs": {
+ "module": "es6",
+ "in-source": true
+ },
+ "suffix": ".bs.js",
+ "sources": [
+ {
+ "dir": "src",
+ "subdirs": true
+ }
+ ],
+ "bs-dependencies": ["reason-react", "reason-react-native"]
+}
+```
+
+👀 _For details about this file, please refer to
+[BuckleScript Configuration documentation](https://bucklescript.github.io/docs/en/build-configuration)._
+
+When it's done, you are ready to use Reason React Native !
+
+---
+
+## Using Reason React Native
+
+@todo move here
+[what's in the template readme](https://github.com/reasonml-community/reason-react-native/tree/master/react-native-template-reason#react-native-helloworld)
+
+### Using JavaScript components from Reason
+
+@todo check out
+[Reason React interop page](https://reasonml.github.io/reason-react/docs/en/components#interop).
+
+You can also browse the source of
+[reason-react-native](https://github.com/reasonml-community/reason-react-native/tree/master/reason-react-native/src)
+because that's exactly what this project is doing!
+
+### Using Reason React Native components from JavaScript
+
+@todo Meanwhile, check out
+[Reason React interop page](https://reasonml.github.io/reason-react/docs/en/components#interop)
+
+---
+
+👉 At this step, you should check our in-depth
+[Example](/reason-react-native/en/docs/example/) or our
+[Cheatsheet](/reason-react-native/en/docs/cheatsheet/)
 
 ---