Add directory details to packages/* package.json (#6826)

Specifying the directory as part of the repository field in a
package.json allows third party tools to provide better support when
working with monorepos. For example, it allows them to correctly
construct a commit diff for a specific package.

This format was accepted by npm in [npm/rfcs#19](https://github.com/npm/rfcs/pull/19).

packages/react-scripts/package.json

@@ -2,7 +2,11 @@
   "name": "react-scripts",
   "version": "2.1.8",
   "description": "Configuration and scripts for Create React App.",
-  "repository": "facebook/create-react-app",
+  "repository": {
+    "type" : "git",
+    "url" : "https://github.com/facebook/create-react-app.git",
+    "directory": "packages/react-scripts"
+  },
   "license": "MIT",
   "engines": {
     "node": ">=8.10"
@@ -59,7 +63,7 @@
     "pnp-webpack-plugin": "1.2.1",
     "postcss-flexbugs-fixes": "4.1.0",
     "postcss-loader": "3.0.0",
-    "postcss-normalize": "7.0.1",   
+    "postcss-normalize": "7.0.1",
     "postcss-preset-env": "6.6.0",
     "postcss-safe-parser": "4.0.1",
     "react-app-polyfill": "^0.2.2",