Docs: Add block patterns list component readme

[JustinyAhin]

Description

Added documentation for the block patterns list component (see #22891)

How has this been tested?

N/A, documentation only

Types of changes

Documentation

Checklist:

• [n/a] My code is tested.
• [n/a] My code follows the WordPress code style.
• [n/a] My code follows the accessibility standards.
• [n/a] My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR.

[JustinyAhin]

@ntsekouras I was wondering if it is necessary to add the onClickPattern={ onClick } to this code sample.

[JustinyAhin]

Also, I was wondering if there could be ways I can make these code samples more detailed. Til now, for the packages I documented, I basically added a const with a simple use case of the component.

I know these packages component are not intended to be uses by third parties, but was just wondering.

[youknowriad]

This component requires three props

shownPatterns={ shownBlockPatterns }
blockPatterns={ shownBlockPatterns }
onClickPattern={ onSelectBlockPattern }

Ideally, we pass a valid prop and explain what these props are about. (Some READMEs have a props section for the explanations)

[JustinyAhin]

Still having to find what the props do exactly. On my list for next week.

[ntsekouras]

Something has been mixed up here. Can you rebase to include only your changes in the PR?

[gziolo]

Thank you for the improvements to the block editor documentation :)