add docs

docs/reference-guides/block-api/block-transforms.md

@@ -228,7 +228,7 @@ When pasting content it's possible to define a [content model](https://html.spec
 When writing `raw` transforms you can control this by supplying a `schema` which describes allowable content and which will be applied to clean up the pasted content before attempting to match with your block. The schemas are passed into [`cleanNodeList` from `@wordpress/dom`](https://github.com/wordpress/gutenberg/blob/trunk/packages/dom/src/dom/clean-node-list.js); check there for a [complete description of the schema](https://github.com/wordpress/gutenberg/blob/trunk/packages/dom/src/phrasing-content.js).
 
 ```js
-schema = { span: { children: { '#text': {} } } }
+schema = { span: { children: { '#text': {} } } };
 ```
 
 **Example: a custom content model**
@@ -237,8 +237,8 @@ Suppose we want to match the following HTML snippet and turn it into some kind o
 
 ```html
 <div data-post-id="13">
-    <h2>The Post Title</h2>
-    <p>Some <em>great</em> content.</p>
+	<h2>The Post Title</h2>
+	<p>Some <em>great</em> content.</p>
 </div>
 ```
 
@@ -270,7 +270,7 @@ A transformation of type `shortcode` is an object that takes the following param
 
 -   **type** _(string)_: the value `shortcode`.
 -   **tag** _(string|array)_: the shortcode tag or list of shortcode aliases this transform can work with.
--   **transform** _(function, optional): a callback that receives the shortcode attributes as the first argument and the [WPShortcodeMatch](/packages/shortcode/README.md#next) as the second. It should return a block object or an array of block objects. When this parameter is defined, it will take precedence over the `attributes` parameter.
+-   **transform** \_(function, optional): a callback that receives the shortcode attributes as the first argument and the [WPShortcodeMatch](/packages/shortcode/README.md#next) as the second. It should return a block object or an array of block objects. When this parameter is defined, it will take precedence over the `attributes` parameter.
 -   **attributes** _(object, optional)_: object representing where the block attributes should be sourced from, according to the attributes shape defined by the [block configuration object](./block-registration.md). If a particular attribute contains a `shortcode` key, it should be a function that receives the shortcode attributes as the first arguments and the [WPShortcodeMatch](/packages/shortcode/README.md#next) as second, and returns a value for the attribute that will be sourced in the block's comment.
 -   **isMatch** _(function, optional)_: a callback that receives the shortcode attributes per the [Shortcode API](https://codex.wordpress.org/Shortcode_API) and should return a boolean. Returning `false` from this function will prevent the shortcode to be transformed into this block.
 -   **priority** _(number, optional)_: controls the priority with which a transform is applied, where a lower value will take precedence over higher values. This behaves much like a [WordPress hook](https://codex.wordpress.org/Plugin_API#Hook_to_WordPress). Like hooks, the default priority is `10` when not otherwise set.
@@ -336,3 +336,25 @@ transforms: {
     ]
 },
 ```
+
+## `ungroup` blocks
+
+Via the optional `transforms` key of the block configuration, blocks can use the `ungroup` subkey to define which inner blocks of a grouping block can be extracted, replacing the block.
+
+If a block has an `ungroup` transform, it is considered ungroupable, without the requirement of being the default grouping block. The UI used to ungroup a block with this API, is the same with the one used for the default grouping block. In order for the ugroup UI to render, we must have a single grouping block selected, which also contains some inner blocks.
+
+**ungroup** is a callback function that receives the attributes and inner blocks of the block being processed. It should return an array of block objects.
+
+Example:
+
+```js
+export const settings = {
+	title: 'My grouping Block Title',
+	description: 'My grouping block description',
+	/* ... */
+	transforms: {
+		ungroup: ( attributes, innerBlocks ) =>
+			innerBlocks.flatMap( ( innerBlock ) => innerBlock.innerBlocks ),
+	},
+};
+```