feat(ui-icons): add new redo and undo icons and modify the documentation page

Author: git-nandor

docs/contributor-docs/adding-icons.md

@@ -25,7 +25,7 @@ type: code
 </svg>
 ```
 
-- The files cannot contain [clipping paths](https://developer.mozilla.org/en-US/docs/Web/SVG/Element/clipPath)! Sadly, when the Designers export icons from Figma, most of the time they have a clipping path around the whole canvas. If the source code has them, manually refactor the code, e.g:
+- The files cannot contain [clipping paths](https://developer.mozilla.org/en-US/docs/Web/SVG/Element/clipPath)! Sadly, when the Designers export icons from Figma, most of the time they have a clipping path around the whole canvas. When an SVG includes clipping paths, the `Icon Font` variant may not render correctly. Specifically, the use of `<g clip-path="...">` and `<clipPath id="...">` elements can cause rendering issues. If the source code has them, manually refactor the code, e.g:
 
 ```js
 ---

packages/ui-icons/icons.config.js

@@ -136,9 +136,11 @@ const bidirectional = [
   'open-folder',
   'outdent',
   'outdent2',
+  'undo',
   'quiz-stats-high',
   'quiz-stats-low',
   'quiz',
+  'redo',
   'replied',
   'reply-2',
   'reply-all-2',