INTRODUCTION
------------
This module provides a CKEditor 5 toolbar button that inserts semantic HTML5
blockquote attribution markup:

  <figure>
    <blockquote>...</blockquote>
    <figcaption>...</figcaption>
  </figure>

It is a CKEditor 5 port of the original CKEditor 4-only module.

INSTALLATION
------------
1. Place this module in web/modules/custom or web/modules/contrib.
2. Enable CKEditor Blockquote Attribution.
3. Edit the desired text format at /admin/config/content/formats.
4. Make sure the format uses CKEditor 5.
5. Drag the "Blockquote with Attribution" button into the active toolbar.
6. Save the text format.

REQUIREMENTS
------------
Drupal core CKEditor 5 module.

ALLOWED HTML
------------
The module declares these CKEditor 5 elements for Drupal's HTML restrictions:

  <figure>
  <figure class>
  <blockquote>
  <blockquote cite>
  <figcaption>
  <figcaption class>
  <cite>

USE
---
Select the text to quote, click the Blockquote with Attribution button, and
enter the source attribution. The selected content is wrapped in a blockquote
inside a figure, with the attribution added as a figcaption.

NOTES
-----
CKEditor 5 is not API-compatible with CKEditor 4. The old CKEditor 4 plugin
class and CKEDITOR.plugins.add() JavaScript have been replaced by:

  ckeditor_blockquote_attribution.ckeditor5.yml
  ckeditor_blockquote_attribution.libraries.yml
  js/build/blockquote_attribution.js

This port intentionally uses a simple browser prompt for the attribution field.
A future enhancement could replace that with a Drupal modal dialog or a CKEditor
5 contextual balloon form.