docs: update apiDir docs to mention v4 programming model

Author: geoffrich

README.md

@@ -94,6 +94,8 @@ The directory where the `sk_render` Azure function for SSR will be placed. Most
 
 By default, the adapter will output the `sk_render` Azure function for SSR in the `build/server` folder. If you want to output it to a different directory instead (e.g. if you have additional Azure functions to deploy), you can set this option.
 
+**Note:** since the `sk_render` function is written using the [v4 Node.js programming model](https://learn.microsoft.com/en-us/azure/azure-functions/functions-reference-node?tabs=javascript%2Cwindows%2Cazure-cli&pivots=nodejs-model-v4), any other Azure functions you deploy with your Static Web App [need to also be written using v4](https://learn.microsoft.com/en-us/azure/azure-functions/functions-node-upgrade-v4?tabs=v4&pivots=programming-language-javascript).
+
 ```js
 import azure from 'svelte-adapter-azure-swa';
 
@@ -130,6 +132,17 @@ custom/
         └── index.js
 ```
 
+The `main` field in your `package.json` [needs to use a glob pattern](https://learn.microsoft.com/en-us/azure/azure-functions/functions-reference-node?tabs=javascript%2Cwindows%2Cazure-cli&pivots=nodejs-model-v4#registering-a-function) that includes both the `sk_render/index.js` entrypoint as well as the entrypoints for your other Azure functions. Example `package.json`:
+
+```json
+{
+	"main": "**/index.js",
+	"dependencies": {
+		"@azure/functions": "^4"
+	}
+}
+```
+
 Also note that the adapter reserves the folder prefix `sk_render` and API route prefix `sk_render` for Azure functions generated by the adapter. So, if you use a custom API directory, you cannot have any other folder starting with `sk_render` or functions available at the `sk_render` route, since these will conflict with the adapter's Azure functions.
 
 ### staticDir