add update script

Author: kentcdodds

package.json

@@ -35,6 +35,7 @@
     "postinstall": "cd ./epicshop && npm install && cd ./epic-me && npm install",
     "start": "npx --prefix ./epicshop epicshop start",
     "dev": "npx --prefix ./epicshop epicshop start",
+    "update": "npx --prefix ./epicshop epicshop update",
     "test": "npm run test --silent --prefix playground",
     "test:e2e": "npm run test:e2e --silent --prefix playground",
     "test:e2e:dev": "npm run test:e2e:dev --silent --prefix playground",