feat(prettyDOM): expose prettyDOM

Closes #86

Author: Kent C. Dodds

src/index.js

@@ -1,6 +1,12 @@
 import ReactDOM from 'react-dom'
 import {Simulate} from 'react-dom/test-utils'
-import {bindElementToQueries, wait, fireEvent, waitForElement} from 'dom-testing-library'
+import {
+  bindElementToQueries,
+  wait,
+  fireEvent,
+  waitForElement,
+  prettyDOM,
+} from 'dom-testing-library'
 
 function render(ui, {container = document.createElement('div')} = {}) {
   ReactDOM.render(ui, container)
@@ -48,4 +54,5 @@ export {
   fireEvent,
   renderIntoDocument,
   cleanup,
+  prettyDOM,
 }