create-react-app: tweaks

- Use `npm run` in tests instead of yarn
- Documented issue with webpack version mismatch

README.md

@@ -1,3 +1,7 @@
+### :warning: Tweaks
+
+- Running tests with `SKIP_PREFLIGHT_CHECK=true npm t` since there are webpack version mismatch warnings
+
 # Create React App [![Build Status](https://dev.azure.com/facebook/create-react-app/_apis/build/status/facebook.create-react-app?branchName=master)](https://dev.azure.com/facebook/create-react-app/_build/latest?definitionId=1&branchName=master) [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-green.svg)](https://github.com/facebook/create-react-app/blob/master/CONTRIBUTING.md)
 
 Create React apps with no build configuration.

lerna.json

@@ -1,6 +1,6 @@
 {
   "lerna": "2.6.0",
-  "npmClient": "yarn",
+  "npmClient": "arborist",
   "useWorkspaces": true,
   "version": "independent",
   "changelog": {

package.json

@@ -9,7 +9,7 @@
     "create-react-app": "node tasks/cra.js",
     "e2e": "tasks/e2e-simple.sh",
     "e2e:docker": "tasks/local-test.sh",
-    "postinstall": "cd packages/react-error-overlay/ && yarn build:prod",
+    "postinstall": "cd packages/react-error-overlay/ && npm run build:prod",
     "publish": "tasks/publish.sh",
     "start": "cd packages/react-scripts && node bin/react-scripts.js start",
     "screencast": "node ./tasks/screencast.js",