fix(shopify): standardizing the pre-release banner (#1268)

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> [!NOTE]
> **Low Risk**
> Documentation-only change limited to the README pre-release notice; no
runtime or API behavior is affected.
> 
> **Overview**
> Updates the `shopify-oxygen` SDK README pre-release banner to
standardize the warning: removes the beta/production-language and
replaces it with a *pre-release/no backwards-compatibility* notice, plus
explicit guidance to pin minor versions and review `CHANGELOG.md` before
upgrading.
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
b68cdde. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
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Author: joker23

packages/sdk/shopify-oxygen/README.md

@@ -10,7 +10,10 @@ LaunchDarkly Server SDK for Shopify Oxygen Runtimes
 # ⛔️⛔️⛔️⛔️
 
 > [!CAUTION]
-> *This version of the SDK is a **beta** version and should not be considered ready for production use while this message is visible.*
+> This SDK is in pre-release and not subject to backwards compatibility 
+> guarantees. The API may change based on feedback.
+>
+> Pin to a specific minor version and review the [changelog](./CHANGELOG.md) before upgrading.
 
 # ☝️☝️☝️☝️☝️☝️