docs: react proxy sdk: explain clientKey and other config vars.

website/docs/sdks/proxy-react.md

@@ -3,19 +3,45 @@ id: proxy-react
 title: React proxy SDK
 ---
 
-> This library is meant to be used with the [unleash-proxy](https://github.com/Unleash/unleash-proxy). The proxy application layer will sit between your unleash instance and your client applications, and provides performance and security benefits. DO NOT TRY to connect this library directly to the unleash instance, as the datasets follow different formats because the proxy only returns evaluated toggle information.
+This library is meant to be used with the [unleash-proxy](https://github.com/Unleash/unleash-proxy). The proxy application layer will sit between your unleash instance and your client applications, and provides performance and security benefits. DO NOT TRY to connect this library directly to the unleash instance, as the datasets follow different formats because the proxy only returns evaluated toggle information.
 
-# Installation
+For more detailed information, check out [the React Proxy SDK on GitHub](https://github.com/Unleash/proxy-client-react).
 
-```
+
+## Installation
+
+```sh
 npm install @unleash/proxy-client-react
 // or
 yarn add @unleash/proxy-client-react
 ```
 
-Import the provider like this in your entrypoint file (typically index.js/ts):
+## Initialize the client
+
+The snippet below shows you how to initialize the client. We recommend that you do this in your entry point file (typically index.js/ts) to ensure that you only have _one_ instance of it.
+
+The configuration variables are:
+- **`url`**
+
+    Your proxy's URL.
+- **`clientKey`**
+
+    One of your proxy's [designated client keys (also known as proxy secrets)](unleash-proxy#configuration-variables).
+
+- **`refreshInterval`**
 
-```js
+  How often (in seconds) the client should poll the proxy for updates.
+
+- **`appName`**
+
+  The name of your application. It's only used for identifying your application and can be whatever you want it to be.
+
+- **`environment`**
+
+  The environment that your application runs in. This corresponds to the environment field in [the Unleash Context](../user_guide/unleash-context.md). Note that this is separate from the newer [Environments feature](../user_guide/environments.md).
+
+
+```jsx
 import FlagProvider from '@unleash/proxy-client-react';
 
 const config = {
@@ -36,9 +62,11 @@ ReactDOM.render(
 );
 ```
 
+## How to check feature toggle states
+
 To check if a feature is enabled:
 
-```js
+```jsx
 import { useFlag } from '@unleash/proxy-client-react';
 
 const TestComponent = () => {
@@ -55,7 +83,7 @@ export default TestComponent;
 
 To check variants:
 
-```js
+```jsx
 import { useVariant } from '@unleash/proxy-client-react';
 
 const TestComponent = () => {
@@ -72,11 +100,11 @@ const TestComponent = () => {
 export default TestComponent;
 ```
 
-## Updating context
+## How to update the Unleash Context
 
 Follow the following steps in order to update the unleash context:
 
-```js
+```jsx
 import { useUnleashContext, useFlag } from '@unleash/proxy-client-react'
 
 const MyComponent = ({ userId }) => {