message: build(aio): prevent Windows error on `serve-and-sync`
  Running `yarn start` (which watches the `src/` directory) and
  `yarn docs-watch` (which cleans up files in `src/generated/api/`) often
  results in `ENOTEMPTY` errors.
  This commit solves it by ensuring that `yarn docs` has been completed
  before running `yarn start`.
  PR Close
diff: "docs-lint": "eslint --ignore-path=\"tools/transforms/.eslintignore\" tools/transforms",
  "docs-test": "node tools/transforms/test.js",
  "tools-test": "./scripts/deploy-to-firebase.test.sh && yarn docs-test && yarn boilerplate:test && jasmine tools/ng-packages-installer/index.spec.js",
  - "serve-and-sync": "concurrently --kill-others \"yarn docs-watch\" \"yarn start\"",
  + "preserve-and-sync": "yarn docs",
  + "serve-and-sync": "concurrently --kill-others \"yarn docs-watch --watch-only\" \"yarn start\"",
  "boilerplate:add": "node ./tools/examples/example-boilerplate add",
  "boilerplate:remove": "node ./tools/examples/example-boilerplate remove",
  "boilerplate:test": "node tools/examples/test.js",
  