Readme tweaks

Author: bvaughn

README.md

@@ -2,23 +2,38 @@
 
 Sample reusable React error boundary component for React 16+
 
+The simplest way to use a boundary is to wrap it around any component that may throw an error.
+This will handle errors thrown by that component's descendents also.
+
 ```jsx
 import ErrorBoundary from 'react-error-boundary';
 
-// The simplest way to use a boundary;
-// Wrap around any component that may throw an error:
 <ErrorBoundary>
   <ComponentThatMayError />
 </ErrorBoundary>
+```
+
+You can also react to errors (eg for logging) by providing an `onError` callback:
+
+```jsx
+import ErrorBoundary from 'react-error-boundary';
+
+const myErrorHandler = (error: Error, componentStack: string) => {
+  // ...
+};
 
-// You can also react to errors (eg for logging):
-const myErrorHandler = (error, componentStack) => {/* ... */}
 <ErrorBoundary onError={myErrorHandler}>
   <ComponentThatMayError />
 </ErrorBoundary>
+```
+
+You can also customize the fallback appearance:
+
+```jsx
+const MyFallbackComponent = ({ componentStack, error }) => (
+  <div/>
+)
 
-// You can also customize the fallback appearance:
-const MyFallbackComponent = ({ componentStack, error }) => (/* ... */)
 <ErrorBoundary FallbackComponent={MyFallbackComponent}>
   <ComponentThatMayError />
 </ErrorBoundary>