add pre-commit

.pre-commit-config.yaml

@@ -0,0 +1,14 @@
+repos:
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.0.1
+    hooks:
+      - id: check-yaml
+      - id: end-of-file-fixer
+      - id: trailing-whitespace
+      - id: check-merge-conflict
+  - repo: https://github.com/pre-commit/mirrors-prettier
+    rev: "v2.4.1" # Use the sha / tag you want to point at
+    hooks:
+      - id: prettier
+        additional_dependencies:
+          - prettier@2.4.1