Expanded register_models() docs for async

docs/plugins/advanced-model-plugins.md

@@ -5,6 +5,8 @@ The {ref}`model plugin tutorial <tutorial-model-plugin>` covers the basics of de
 
 This document covers more advanced topics.
 
+(advanced-model-plugins-async)=
+
 ## Async models
 
 Plugins can optionally provide an asynchronous version of their model, suitable for use with Python [asyncio](https://docs.python.org/3/library/asyncio.html). This is particularly useful for remote models accessible by an HTTP API.
@@ -52,6 +54,7 @@ def register_models(register):
 ```
 
 (advanced-model-plugins-attachments)=
+
 ## Attachments for multi-modal models
 
 Models such as GPT-4o, Claude 3.5 Sonnet and Google's Gemini 1.5 are multi-modal: they accept input in the form of images and maybe even audio, video and other formats.

docs/plugins/plugin-hooks.md

@@ -42,5 +42,20 @@ class HelloWorld(llm.Model):
     def execute(self, prompt, stream, response):
         return ["hello world"]
 ```
+If your model includes an async version, you can register that too:
+
+```python
+class AsyncHelloWorld(llm.AsyncModel):
+    model_id = "helloworld"
+
+    async def execute(self, prompt, stream, response):
+        return ["hello world"]
+
+@llm.hookimpl
+def register_models(register):
+    register(HelloWorld(), AsyncHelloWorld(), aliases=("hw",))
+```
+This demonstrates how to register a model with both sync and async versions, and how to specify an alias for that model.
+
+The {ref}`model plugin tutorial <tutorial-model-plugin>` describes how to use this hook in detail. Asynchronous models {ref}`are described here <advanced-model-plugins-async>`.
 
-{ref}`tutorial-model-plugin` describes how to use this hook in detail.