add pre-commit and prettier

.pre-commit-config.yaml

@@ -0,0 +1,25 @@
+repos:
+  - repo: https://github.com/prettier/prettier
+    rev: '2.0.5'
+    hooks:
+      - id: prettier
+        files: "\\.(\
+          css|less|scss\
+          |graphql|gql\
+          |html\
+          |js|jsx\
+          |json\
+          |ts|tsx\
+          |vue\
+          |yaml|yml\
+          )$"
+  - repo: https://github.com/prettier/prettier
+    rev: '2.0.5'
+    hooks:
+      - id: prettier
+        name: prettier-markdown
+        entry: prettier --write --parser mdx
+        files: "\\.(\
+          |md|markdown|mdown|mkdn\
+          |mdx\
+          )$"

.prettierrc.json

@@ -0,0 +1,8 @@
+{
+  "tabWidth": 2,
+  "semi": false,
+  "singleQuote": true,
+  "printWidth": 80,
+  "quoteProps": "as-needed",
+  "jsxSingleQuote": true
+}

package.json

@@ -37,6 +37,7 @@
     "theme-ui": "^0.3.1"
   },
   "devDependencies": {
+    "prettier": "2.0.5",
     "redux-devtools-extension": "^2.13.8"
   }
 }