message: docs: remove extra word in grammar
diff: @@ -323,7 +323,7 @@ Redoc.init(specOrSpecUrl, options, element, callback?)
  - `specOrSpecUrl` is either JSON object with specification or an URL to the spec in `JSON` or `YAML` format
  - `options` [options object](#redoc-options-object)
  - `element` DOM element to put ReDoc into
  -- `callback` (optional) - callback to be called after Redoc has been fully rendered. It is also called also on errors with error as the first argument
  +- `callback` (optional) - callback to be called after Redoc has been fully rendered. It is also called on errors with error as the first argument
  ```js
  Redoc.init('http://petstore.swagger.io/v2/swagger.json', {
  