Add prettier for typescript

Author: wooorm

package.json

@@ -59,7 +59,7 @@
     "xo": "^0.26.0"
   },
   "scripts": {
-    "format": "remark . -qfo && prettier --write \"**/*.js\" && xo --fix",
+    "format": "remark . -qfo && prettier --write \"**/*.{js,ts}\" && xo --fix",
     "build-bundle": "browserify . -s mdastUtilTOC > mdast-util-toc.js",
     "build-mangle": "browserify . -s mdastUtilTOC -p tinyify > mdast-util-toc.min.js",
     "build": "npm run build-bundle && npm run build-mangle",