Add prettier check to CI (facebook#4219)

Author: johnf

website/.prettierignore

@@ -0,0 +1 @@
+src/theme

website/package.json

@@ -30,9 +30,10 @@
     "lint:versioned": "eslint versioned_docs/**",
     "lint:markdown": "remark ../docs --quiet -r .remarkrc.mjs",
     "lint:markdown:versioned": "remark ./versioned_docs --quiet -r .remarkrc.mjs",
+    "lint:format": "prettier --check {{core,src}/**/*.js,*.js} ../docs/*.md {versioned_docs/**/*.md,blog/*.md} src/**/*.{scss,css}",
     "language:lint": "cd ../ && alex && case-police 'docs/*.md' -p brands,general,products,softwares -d ./website/react-native-dict.json",
     "language:lint:versioned": "cd ../ && alex . && case-police '**/*.md' -p brands,general,products,softwares -d ./website/react-native-dict.json",
-    "ci:lint": "yarn lint && yarn lint:examples && yarn lint:versioned && yarn language:lint:versioned && yarn lint:markdown",
+    "ci:lint": "yarn lint && yarn lint:examples && yarn lint:versioned && yarn language:lint:versioned && yarn lint:markdown && yarn lint:format",
     "pwa:generate": "npx pwa-asset-generator ./static/img/header_logo.svg ./static/img/pwa --padding '40px' --background 'rgb(32, 35, 42)' --icon-only --opaque true"
   },
   "browserslist": {

website/src/css/customTheme.scss

@@ -589,14 +589,15 @@ article header h1 {
   line-height: 3rem;
 }
 
-article header h2, {
+article header h2 {
   line-height: 3rem;
 
   a {
     color: var(--ifm-font-color-base);
     font-size: 2.5rem;
 
-    &:hover, &:focus {
+    &:hover,
+    &:focus {
       color: var(--ifm-font-color-base);
       opacity: 0.8;
     }