feat(starters): Add .prettierrc to starters (#11786)

* feature(prettier): Add .prettierrc to starters

* Add format script and prettier and prettier as a dev dependency

* Move format script up after develop

* feature(prettier): Add .prettierrc to starters

* Add format script and prettier and prettier as a dev dependency

* Move format script up after develop

* Add .prettierrc to filetree on README files of all starters

* Remove duplication of devDependencies on hello-world starter

.prettierrc

@@ -0,0 +1,7 @@
+{
+  "endOfLine": "lf",
+  "semi": false,
+  "singleQuote": false,
+  "tabWidth": 2,
+  "trailingComma": "es5"
+}

README.md

@@ -48,6 +48,7 @@ A quick look at the top-level files and directories you'll see in a Gatsby proje
     ├── node_modules
     ├── src
     ├── .gitignore
+    ├── .prettierrc
     ├── gatsby-browser.js
     ├── gatsby-config.js
     ├── gatsby-node.js

package.json

@@ -7,6 +7,7 @@
   "scripts": {
     "build": "gatsby build",
     "develop": "gatsby develop",
+    "format": "prettier --write src/**/*.{js,jsx}",
     "start": "npm run develop",
     "serve": "gatsby serve",
     "test": "echo \"Write tests! -> https://gatsby.app/unit-testing\""
@@ -16,6 +17,9 @@
     "react": "^16.8.3",
     "react-dom": "^16.8.3"
   },
+  "devDependencies": {
+    "prettier": "^1.16.4"
+  },
   "repository": {
     "type": "git",
     "url": "https://github.com/gatsbyjs/gatsby-starter-hello-world"

yarn.lock

@@ -6986,7 +6986,7 @@ prepend-http@^1.0.1:
   resolved "https://registry.yarnpkg.com/prepend-http/-/prepend-http-1.0.4.tgz#d4f4562b0ce3696e41ac52d0e002e57a635dc6dc"
   integrity sha1-1PRWKwzjaW5BrFLQ4ALlemNdxtw=
 
-prettier@^1.16.0:
+prettier@^1.16.0, prettier@^1.16.4:
   version "1.16.4"
   resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.16.4.tgz#73e37e73e018ad2db9c76742e2647e21790c9717"
   integrity sha512-ZzWuos7TI5CKUeQAtFd6Zhm2s6EpAD/ZLApIhsF9pRvRtM1RFo61dM/4MSRUA0SuLugA/zgrZD8m0BaY46Og7g==