Docs: Update RichTextToolbarButton link in docs

[Infinite-Null]

What?

Closes #70802

Fix broken RichTextToolbarButton documentation link in Format API guide.

Why?

The Format API guide contains a broken link to RichTextToolbarButton documentation that returns a 404 error, leaving developers without proper reference material. The current link points to /packages/block-editor/src/components/rich-text#richtexttoolbarbutton which doesn't exist, causing confusion for developers trying to follow the guide.

How?

• Fixed broken documentation link: Updated the RichTextToolbarButton reference in the "Additional resources" section from the non-existent /packages/block-editor/src/components/rich-text#richtexttoolbarbutton to the correct working documentation URL /packages/editor/README.md#richtexttoolbarbutton

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Co-authored-by: Infinite-Null <ankitkumarshah@git.wordpress.org>
Co-authored-by: fabiankaegy <fabiankaegy@git.wordpress.org>
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[fabiankaegy]

We should use the version of there readme in the @wordpress/block-editor package instead since the one in @wordpress/editor is deprecated

Suggested change

	- Components: [`RichTextToolbarButton`](/packages/editor/README.md#richtexttoolbarbutton)
	- Components: [`RichTextToolbarButton`](/packages/block-editor/README.md#richtexttoolbarbutton)

[Infinite-Null]

Hi @fabiankaegy,
Thank you for the feedback 🙌. I have updated the PR please review it at your convenience.