Add an example of how to use async/await to the README

Author: jedwards1211

README.md

@@ -179,6 +179,17 @@ it("should change the state", function (done) {
 
 Notice how `.notify(done)` is hanging directly off of `.should`, instead of appearing after a promise assertion. This indicates to Chai as Promised that it should pass fulfillment or rejection directly through to the testing framework. Thus, the above code will fail with a Chai as Promised error (`"expected promise to be fulfilled…"`) if `promise` is rejected, but will fail with a simple Chai error (`expected "before" to equal "after"`) if `otherState` does not change.
 
+### Working with `async`/`await` and Promise-Friendly Test Runners
+
+Since any assertion that must wait on a promise returns a promise itself, if you're able to use `async`/`await` and your test runner supports returning a promise from test methods, you can await assertions in tests.  In many cases you can avoid using Chai as Promised at all by performing a synchronous assertion after an `await`, but awaiting `rejectedWith` is often more convenient than using `try`/`catch` blocks without Chai as Promised:
+
+```javascript
+it('should work well with async/await', async () => {
+  (await Promise.resolve(42)).should.equal(42)
+  await Promise.reject(new Error()).should.be.rejectedWith(Error);
+});
+```
+
 ### Multiple Promise Assertions
 
 To perform assertions on multiple promises, use `Promise.all` to combine multiple Chai as Promised assertions: