Update usage advice of husky to 1.0 (facebook#5071)

Husky had an overhaul of the API, see https://github.com/typicode/husky
Therefore the usage advice here has been adjusted.

template/README.md

@@ -326,13 +326,14 @@ yarn add husky lint-staged prettier
 
 Now we can make sure every file is formatted correctly by adding a few lines to the `package.json` in the project root.
 
-Add the following line to `scripts` section:
+Add the following field to the `package.json` section:
 
 ```diff
-  "scripts": {
-+   "precommit": "lint-staged",
-    "start": "react-scripts start",
-    "build": "react-scripts build",
++  "husky": {
++    "hooks": {
++      "pre-commit": "lint-staged"
++    }
++  }
 ```
 
 Next we add a 'lint-staged' field to the `package.json`, for example: