message: docs: fix a package name in How to install
diff: @@ -13,7 +13,7 @@ Validate `manifest.json` of kintone plugin. Used in [@kintone/plugin-packer](htt
  ## How to install
  ```console
  -$ npm install @teppeis/kintone-plugin-packer
  +$ npm install @kintone/plugin-manifest-validator
  ```
  ## Usage
  