Add/block types list component readme (#25066)

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* Update block types list readme

* Update block types list readme

* Update JSX code sample

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packages/block-editor/src/components/block-types-list/README.md

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+# Block Types List
+
+The `BlockTypesList` component lets users display a list of blocks in different interfaces or as a result of certain actions. It is also possible to select one of the blocks in the list to insert it into the editor.
+
+This component is present in the block insertion tab, the reusable blocks tab and the quick block insertion modal in the editor.
+
+![Block types list in the block inserter tab](https://make.wordpress.org/core/files/2020/09/block-types-list-emplacement-1.png)
+
+![Block types list in the reusables blocks tab](https://make.wordpress.org/core/files/2020/09/block-types-list-emplacement-2.png)
+
+![Block types list in the quick inserter modal](https://make.wordpress.org/core/files/2020/09/block-types-list-emplacement-3.png)
+
+## Table of contents
+
+1. [Development guidelines](#development-guidelines)
+2. [Related components](#related-components)
+
+## Development guidelines
+
+### Usage
+
+Renders a list of blocks types.
+
+```jsx
+import { BlockTypesList } from '@wordpress/block-editor';
+
+const MyBlockTypesList = () => <BlockTypesList items={ filteredItems } />;;
+```
+
+### Props
+
+#### items
+
+The blocks that will be displayed in the block list.
+
+-   Type: `Array<Block>`
+-   Required: Yes
+
+## Related components
+
+Block Editor components are components that can be used to compose the UI of your block editor. Thus, they can only be used under a [`BlockEditorProvider`](https://github.com/WordPress/gutenberg/blob/master/packages/block-editor/src/components/provider/README.md) in the components tree.