BlockSwitcher: Add README and JS doc for BlockSwitcher component

packages/block-editor/src/components/block-switcher/README.md

@@ -0,0 +1,26 @@
+# Block Switcher
+
+The `BlockSwitcher` component provides a toolbar dropdown menu for converting between block types, applying block styles, and accessing pattern transformations. It appears in the block toolbar when these transformation options are available.
+
+## Usage
+
+Render component to enable block transformations.
+
+```jsx
+import { BlockSwitcher } from '@wordpress/block-editor';
+
+function MyBlockSwitcher() {
+	return (
+		<BlockSwitcher clientIds={['ch1d82m9-d33a-4c12-b5d9-a8927e12b654']} />
+	);
+}
+```
+
+## Props
+
+### clientIds
+
+The client IDs of the blocks that will be displayed in the block list.
+
+-   Type: `Array<String>`
+-   Required: Yes

packages/block-editor/src/components/block-switcher/index.js

@@ -186,6 +186,28 @@ function BlockSwitcherDropdownMenuContents( {
 	);
 }
 
+/**
+ * The `BlockSwitcher` component provides a toolbar dropdown menu for converting
+ * between block types, applying block styles, and accessing pattern
+ * transformations. It appears in the block toolbar when these transformation
+ * options are available.
+ *
+ * @example
+ * ```jsx
+ * import { BlockSwitcher } from '@wordpress/block-editor';
+ *
+ * function MyBlockSwitcher() {
+ *     return (
+ *         <BlockSwitcher clientIds={['ch1d82m9-d33a-4c12-b5d9-a8927e12b654']} />
+ *     );
+ * }
+ * ```
+ *
+ * @param {Object}   props           Component props.
+ * @param {string[]} props.clientIds The client IDs of the blocks that will be displayed in the block list.
+ *
+ * @return {Element} The BlockSwitcher component.
+ */
 export const BlockSwitcher = ( { clientIds } ) => {
 	const {
 		hasContentOnlyLocking,