prettier config

.prettierignore

+package.json
 package-lock.json
 assets/css/dark-mode-preview.scss
 assets/css/just-the-docs.scss

.prettierrc

+{
+  "endOfLine": "lf",
+  "semi": false,
+  "singleQuote": false,
+  "tabWidth": 2,
+  "trailingComma": "es5"
+}