Fix dead link to Jest "expect" docs (#3289)

Closes #3291

Author: alexkrolick

packages/react-scripts/template/README.md

@@ -1235,7 +1235,7 @@ it('sums numbers', () => {
 });
 ```
 
-All `expect()` matchers supported by Jest are [extensively documented here](http://facebook.github.io/jest/docs/expect.html).<br>
+All `expect()` matchers supported by Jest are [extensively documented here](https://facebook.github.io/jest/docs/en/expect.html#content).<br>
 You can also use [`jest.fn()` and `expect(fn).toBeCalled()`](http://facebook.github.io/jest/docs/expect.html#tohavebeencalled) to create “spies” or mock functions.
 
 ### Testing Components