Update README.md (#1821)

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## Summary by CodeRabbit

- Documentation
- Updated the README to describe Lynx as a “core Frontend stack” instead
of “core JavaScript stack,” improving clarity and aligning terminology
with current positioning.
- This change is limited to documentation; there are no modifications to
functionality, APIs, or interfaces.
- Improves onboarding clarity for readers and contributors without
impacting application behavior.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

## Checklist

<!--- Check and mark with an "x" -->

- [ ] Tests updated (or not required).
- [ ] Documentation updated (or not required).
- [ ] Changeset added, and when a BREAKING CHANGE occurs, it needs to be
clearly marked (or not required).

Author: Huxpro

README.md

@@ -6,7 +6,7 @@
 [![X (formerly Twitter) URL](https://img.shields.io/twitter/url?url=https%3A%2F%2Fx.com%2Flynxjs_org&style=social&label=Lynx)](https://x.com/lynxjs_org)
 [![Discord](https://img.shields.io/discord/1345754526174543964?logo=discord&style=social&label=Lynx)](https://discord.gg/mXk7jqdDXk)
 
-This repository contains the **core JavaScript stack** of Lynx, including [ReactLynx][1], [Rspeedy][2], [Lynx for Web][3], and more. For other repositories in the Lynx family, visit our [org homepage](https://github.com/lynx-family).
+This repository contains the **core Frontend stack** of Lynx, including [ReactLynx][1], [Rspeedy][2], [Lynx for Web][3], and more. For other repositories in the Lynx family, visit our [org homepage](https://github.com/lynx-family).
 
 ## Content