Add old renderers disclaimer

Author: gspencergoog

docs/quickstart.md

@@ -2,6 +2,9 @@
 
 Get hands-on with A2UI by running the restaurant finder demo. This guide will have you experiencing agent-generated UI in less than 5 minutes.
 
+> Currently, most renderers in the repo are not yet updated to the latest spec (v0.9), so the messages generated
+> may not be as described in the v0.9 documentation.
+
 ## What You'll Build
 
 By the end of this quickstart, you'll have:

docs/renderers.md

@@ -17,6 +17,9 @@ You have a lot of flexibility, to bring custom comonents to a renderer, or build
 | **Flutter (GenUI SDK)** | Mobile/Desktop/Web | 🚧 In Progress | [Docs](https://docs.flutter.dev/ai/genui) · [Code](https://github.com/flutter/genui) |
 | **React** | Web | 🚧 In Progress | Coming Q1 2026 |
 
+> Currently, most renderers in the repo are not yet updated to the latest spec (v0.9), so the messages generated
+> may not be as described in the v0.9 documentation.
+
 Check the [Roadmap](roadmap.md) for more.
 
 ## How Renderers Work

docs/roadmap.md

@@ -12,6 +12,9 @@ This roadmap outlines the current state and future plans for the A2UI project. T
 | **v0.9** | ✅ Current | Current stable release |
 | **v0.8** | ⏸️ Previous | Initial public release |
 
+> Currently, most renderers in the repo are not yet updated to the latest spec (v0.9), so the messages generated
+> may not be as described in the v0.9 documentation.
+
 Key features:
 
 - ✅ Streaming JSONL message format