Update README.md

Author: notwillk

README.md

@@ -7,6 +7,20 @@
 
 ## Usage
 
-TBD
+This lets you avoid a deeply nested set of providers by defining them as an array.
+
+```javascript
+import ProviderStack from 'react-provider-stack';
+
+function App() {
+  return (
+    <ProviderStack providers={[Provider1, Provider2, Provider3]}>
+      <AppLogic />
+    </ProviderStack
+  );
+}
+```
+
+The only requirement is that each provider is a react component that only takes `children`.
 
 This README was generated by [anansi](https://github.com/ntucker/anansi/tree/master/packages/generator-js#readme).