chore: update documentation

Author: DmitryAnansky

docs/@v2/commands/split.md

@@ -3,17 +3,41 @@
 ## Introduction
 
 The `split` command takes an API description file and creates a [multi-file structure](https://redocly.com/docs/resources/multi-file-definitions/) out of it by extracting referenced parts into standalone, separate files.
-Code samples, components, and paths are split from the root API description into separate files and folders.
-The structure of the unbundled directory corresponds to the structure created by our [openapi-starter](https://github.com/Redocly/openapi-starter) tool.
 The advantage of this approach is making smaller files that are easier to manage and a structure that makes reviewing simpler.
 
-Use the [`bundle`](./bundle.md) command and supply the main file as the entrypoint to get your OpenAPI description in one file.
-Many OpenAPI tools prefer a single file, but `split` and `bundle` allow you to manage your files easily for development, and then prepare a single file for other tools to consume.
-
-{% admonition type="warning" name="OpenAPI 3.x only" %}
-The `split` command supports OpenAPI 3.x descriptions only.
+{% admonition type="warning" name="Supported specifications" %}
+The `split` command supports OpenAPI 3.x, AsyncAPI 2.x, and AsyncAPI 3.x descriptions. OpenAPI 2.x (Swagger) is not supported.
 {% /admonition %}
 
+The parts that get split depend on the type of API description:
+
+**OpenAPI 3.x**
+
+Components, paths, and webhooks are split from the root API description into separate files and folders.
+The structure of the unbundled directory corresponds to the structure created by the [openapi-starter](https://github.com/Redocly/openapi-starter) tool.
+
+- `paths/` - each path item is written to a separate file
+- `webhooks/` - each webhook is written to a separate file (OpenAPI 3.1+)
+- `components/` - schemas, responses, parameters, examples, headers, requestBodies, links, callbacks, and securitySchemes are each split into subdirectories
+
+**AsyncAPI 2.x**
+
+Channels and components are split from the root API description into separate files and folders.
+
+- `channels/` - each channel is written to a separate file
+- `components/` - schemas, messages, securitySchemes, parameters, correlationIds, messageTraits, operationTraits, serverBindings, channelBindings, operationBindings, and messageBindings are each split into subdirectories
+
+**AsyncAPI 3.x**
+
+Channels, operations, and components are split from the root API description into separate files and folders.
+
+- `channels/` - each channel is written to a separate file
+- `operations/` - each operation is written to a separate file
+- `components/` - schemas, messages, securitySchemes, servers, serverVariables, parameters, replies, replyAddresses, correlationIds, messageTraits, operationTraits, tags, externalDocs, serverBindings, channelBindings, operationBindings, and messageBindings are each split into subdirectories
+
+Use the [`bundle`](./bundle.md) command and supply the main file as the entrypoint to get your API description back in one file.
+Many API tools prefer a single file, but `split` and `bundle` allow you to manage your files easily for development, and then prepare a single file for other tools to consume.
+
 ## Usage
 
 ```bash
@@ -36,7 +60,7 @@ redocly split --version
 
 ## Examples
 
-### View successful split message
+### Split an OpenAPI description
 
 This `split` command "unbundles" the specified API description, as defined in `pet.yaml`, into the `openapi` output directory:
 
@@ -52,3 +76,18 @@ Document: pet.yaml is successfully split
 
 pet.yaml: split processed in 33ms
 </pre>
+
+### Split an AsyncAPI description
+
+The `split` command works the same way with AsyncAPI 2.x and AsyncAPI 3.x descriptions:
+
+```bash
+redocly split asyncapi.yaml --outDir=asyncapi
+```
+
+<pre>
+Document: asyncapi.yaml is successfully split
+ and all related files are saved to the directory: asyncapi
+
+asyncapi.yaml: split processed in 25ms
+</pre>