Add more setup details to readme

Author: AlyssaKirstine

Diff for: README.md

@@ -2,8 +2,51 @@
 
 A Gatsby plugin to add `@axe-core/react` accessibility testing to Gatsby markup.
 
-## Installation
+## Install
 
 ```shell
-yarn install @axe-core/react axe-core gatsby-plugin-axe-core-react --dev 
-```
+yarn add @axe-core/react axe-core gatsby-plugin-axe-core-react --dev 
+```
+
+## How to use
+
+```javascript
+// In your gatsby-config.js
+
+plugins: [`gatsby-plugin-axe-core-react`]
+```
+
+or
+
+```javascript
+// In your gatsby-config.js
+
+plugins: [
+  {
+    resolve: 'gatsby-plugin-axe-core-react',
+    options: {
+        axeConfig,
+        axeContext,
+        debounce,
+    },
+  },
+]
+```
+
+React-axe will now print a11y warnings to your browser's console. 🎉
+
+
+### Configuration options
+You can use the following options if you wish to to override the default config.
+
+[**`axeConfig`**](https://www.npmjs.com/package/@axe-core/react#configuration) [object][optional]
+
+The configuration object for axe-core.
+
+[**`axeContext`**](https://github.com/dequelabs/axe-core/blob/master/doc/API.md#context-parameter) [object][optional]
+
+Used to specify which element should and which should not be tested.
+
+[**`debounce`**](https://www.npmjs.com/package/@axe-core/react#debouncing) [number][optional]
+
+The number of milliseconds to wait for component updates to cease before performing an analysis of all the changes.