message: docs: about error format
diff: @@ -19,8 +19,22 @@ $ npm install @teppeis/kintone-plugin-packer
  const validator = require('@teppeis/kintone-plugin-manifest-validator');
  const result = validator(manifestJson);
  -console.log(result.valid); // boolean
  -console.log(result.errors); // [{field: string, message: string}]
  +console.log(result.valid); // true or fals
  +console.log(result.errors); // array of ajv error objects
  +```
  +
  +[ajv error objects](https://github.com/epoberezkin/ajv#validation-errors) is like:
  +
  +```js
  +{
  + dataPath: '.version',
  + keyword: 'type',
  + message: 'should be integer',
  + params: {
  + type: 'integer',
  + },
  + schemaPath: '#/properties/version/type',
  +}
  ```
  ## License
  