Incorrect import statement in the "Creating a custom thread view with a new template" guide

[mabryl]

📝 Provide a description of requested docs changes

In the Creating a custom thread view with a new template guide there's an incorrect import in one of the code snippets.

Currently the import statement looks as follows:

import { UIModel, addListToDropdown, createDropdown } from '@ckeditor/ckeditor5-ui';

The issue is that there is no UIModel in the @ckeditor/ckeditor5-ui package.

The import could be altered to look like this:

import { Model as UIModel, createDropdown, addListToDropdown } from '@ckeditor/ckeditor5-ui';