docs: add "cleanup" section

Author: aleclarson

src/render.js

@@ -8,7 +8,6 @@ import { queryByAPI } from './helpers/queryByAPI';
 import a11yAPI from './helpers/a11yAPI';
 import debugShallow from './helpers/debugShallow';
 import debugDeep from './helpers/debugDeep';
-import cleanup from './cleanup';
 
 type Options = {
   wrapper?: React.ComponentType<any>,

website/docs/API.md

@@ -351,7 +351,7 @@ Defined as:
 function within(instance: ReactTestInstance): Queries
 ```
 
-Perform [queries](./Queries.md) scoped to given element. 
+Perform [queries](./Queries.md) scoped to given element.
 
 :::note
 Please note that additional `render` specific operations like `update`, `unmount`, `debug`, `toJSON` are _not_ included.