docs: add addendum on useId usage with computed (#3262)

* docs: add addendum on useId usage with computed

* docs: refine useId warning with computed

Author: bencodezen

src/api/composition-api-helpers.md

@@ -132,3 +132,7 @@ Used to generate unique-per-application IDs for accessibility attributes or form
   IDs generated by `useId()` are also guaranteed to be stable across the server and client renders, so they can be used in SSR applications without leading to hydration mismatches.
 
   If you have more than one Vue application instance of the same page, you can avoid ID conflicts by giving each app an ID prefix via [`app.config.idPrefix`](/api/application#app-config-idprefix).
+
+  :::warning Caution
+  `useId()` should be not be called inside a `computed()` property as it may cause instance conflicts. Instead, declare the ID outside of `computed()` and reference it within the computed function.
+  :::