📚 Documentation: Async Function documentation needs clearer explanation and examples

### 💭 Description Ref: https://appwrite.io/docs/references/cloud/client-web/functions#createExecution async boolean Execute code in the background. Default value is false. Currently functions timeout after 30 seconds if async = false. So while client code can async wait on a synch function call up to 30 seconds, there are many tasks that will need full async async execution longer than this, such as LLM RAG, emerging GraphRAG, and whatever evolution delivers in this space (as one example).  However, there is no clear concise explanation of the structure of a proper async function that I can find. The template examples all seem to be built around async = false (30 second timeouts) so a clear concise explanation of the server side async support + some working cloud function example code to demonstrate best practice execution would be great. It ultimately makes AW a better product having clear concise docs and a smooth developer UX for fast application development. Also easier from a support perspective when people ask about it just to say sure, here's a link, have at it! ty. ### 👀 Have you spent some time to check if this issue has been raised before? - [X] I checked and didn't find similar issue ### 🏢 Have you read the Code of Conduct? - [X] I have read the [Code of Conduct](https://github.com/appwrite/.github/blob/main/CODE_OF_CONDUCT.md)