message: docs: remove npm downloads badge
diff: @@ -4,7 +4,6 @@ kintone-plugin-packer
  [kintone plugin package.sh](https://github.com/kintone/plugin-sdk) for JavaScript
  [![npm version][npm-image]][npm-url]
  -[![npm downloads][npm-downloads-image]][npm-url]
  ![Node.js Version Support][node-version]
  [![build status][circleci-image]][circleci-url]
  [![windows build status][appveyor-image]][appveyor-url]
  