Documenting innerBlocks in save function

[Lovor01]

There is an undocumented property 'innerBlocks' of props passed to save function. This change attempts to document it with example of use.

What?

Why?

How?

Testing Instructions

Testing Instructions for Keyboard

Screenshots or screencast

[github-actions]

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Co-authored-by: Lovor01 <lovor@git.wordpress.org>
Co-authored-by: gziolo <gziolo@git.wordpress.org>

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[gziolo]

Nice addition, thank you for contributing these explanation.

[gziolo]

It looks like it's a convenient alternative to another way to check inner blocks:

gutenberg/packages/block-library/src/gallery/save.js

Lines 24 to 29 in c979084

	const blockProps = useBlockProps.save( { className } );
	const innerBlocksProps = useInnerBlocksProps.save( blockProps );
	return (
	<figure { ...innerBlocksProps }>
	{ innerBlocksProps.children }

I'm not entirely sure what the difference exactly is. However, I wanted to document it for completeness.