Update TutorialReact.md (#5949)

* adds create-react-app snapshot dependency in docs

The current docs imply you can use Jest snapshots with create-react-app 'out-the-box', however the Snapshot Testing example doesn't work with a fresh install. You need to additionally install `react-test-renderer` as a dependency.

I thought it was more helpful to change the docs, but if it's better to raise the issue elsewhere let me know?!

* Update TutorialReact.md

The current docs imply you can use Jest snapshots with create-react-app 'out-the-box', however the Snapshot Testing example doesn't work with a fresh install. You need to additionally install `react-test-renderer` as a dependency.

I thought it was more helpful to change the docs, but if it's better to raise the issue elsewhere let me know?!

* ran yarn install and yarn lint:md

* amendned text to match w/o CRA code example

docs/TutorialReact.md

@@ -14,8 +14,13 @@ If you are just getting started with React, we recommend using
 [Create React App](https://github.com/facebookincubator/create-react-app). It is
 ready to use and
 [ships with Jest](https://github.com/facebookincubator/create-react-app/blob/master/packages/react-scripts/template/README.md#running-tests)!
-You don't need to do any extra steps for setup, and can head straight to the
-next section.
+You will only need to add `react-test-renderer` for rendering snapshots.
+
+Run
+
+```bash
+yarn add --dev react-test-renderer
+```
 
 ### Setup without Create React App
 

yarn.lock

@@ -8445,7 +8445,7 @@ supports-color@^3.1.2:
   dependencies:
     has-flag "^1.0.0"
 
-supports-color@^5.2.0, supports-color@^5.3.0:
+supports-color@^5.3.0:
   version "5.3.0"
   resolved "https://registry.yarnpkg.com/supports-color/-/supports-color-5.3.0.tgz#5b24ac15db80fa927cf5227a4a33fd3c4c7676c0"
   dependencies: