docs: Preserve SDK alpha and beta notices

Co-Authored-By: GPT-6 <codex@openai.com>

Author: nicohrubec

packages/solidstart/README.md

@@ -12,6 +12,9 @@
 
 The official Sentry SDK for monitoring SolidStart applications.
 
+This SDK is in **Beta**. The API is stable but updates may include minor changes in behavior. Please reach out on
+[GitHub](https://github.com/getsentry/sentry-javascript/issues/new/choose) if you have any feedback or concerns.
+
 ## Documentation
 
 - [Getting started](https://docs.sentry.io/platforms/javascript/guides/solidstart/)