chore(vscode): ease flow usage (jestjs#4569)

* chore(vscode): ease flow usage

Following https://github.com/flowtype/flow-for-vscode#setup they recommend setting `"javascript.validate.enable": false` in workspace settings, otherwise I get errors like "... can only be used in a .ts file".

As I am new to flow and vscode I might be wrong, let me know vscode users contributing to Jest how it works for you today?

* Update settings.json

.vscode/settings.json

@@ -1,16 +1,18 @@
 {
-  "jest.pathToJest": "yarn jest --",
   "editor.rulers": [80],
   "files.exclude": {
     "**/.git": true,
     "**/node_modules": true,
     "**/build": true
   },
+  "editor.formatOnSave": true,
+  "flow.useNPMPackagedFlow": true,
+  "javascript.validate.enable": false,
+  "jest.pathToJest": "yarn jest --",
+  "prettier.eslintIntegration": true,
   "prettier.parser": "flow",
   "prettier.printWidth": 80,
-  "prettier.singleQuote": true,
-  "prettier.trailingComma": "all",
   "prettier.semi": true,
-  "editor.formatOnSave": true,
-  "prettier.eslintIntegration": true
+  "prettier.singleQuote": true,
+  "prettier.trailingComma": "all"
 }