Revise README for maintenance mode announcement (primer#3909)

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <198982749+Copilot@users.noreply.github.com>
Co-authored-by: lesliecdubs <3902488+lesliecdubs@users.noreply.github.com>

Author: 3 people

README.md

@@ -6,12 +6,31 @@
 
 <p align="center">ViewComponents for the Primer Design System.</p>
 
-_Note: This library is under active pre-1.0 development. Breaking changes are likely in patch releases._
+> [!WARNING]
+> As part of GitHub’s move to React-based interfaces, Primer ViewComponents is in maintenance mode as of February 2026.
+>
+> Maintenance mode means:
+>
+> * this project is **not accepting new features, components, or significant enhancements.**
+> * the Primer team at GitHub will continue providing:
+>   * Security updates
+>   * Dependency bumps
+>   * Critical/P0 bug fixes
+> * issues, PRs, and discussions / community Q&A remain open, but maintainer response is not guaranteed
+The Primer team continues to focus its resources on strategic investments that help GitHub and its customers to be successful, while making developers’ lives easier. The Primer design system remains a part of this vision through [guidance](https://primer.style/product/ui-patterns/), [tooling](https://primer.style/product/getting-started/react/), and ready-to-use [React](https://primer.style/product/components/) and [web components](https://github.com/github/github-elements).
+>
+> We encourage internal GitHub consumers to plan to migrate from Primer ViewComponents to [Primer React](https://github.com/primer/react).
+>
+> Non-GitHub consumers should consider forking and maintaining a copy of this repo.
+>
+> Questions may be posted on the [maintenance mode announcement](https://github.com/primer/view_components/discussions/3908). Thank you for your support and interest!
 
 ## Documentation
 
 Visit [https://primer.style/components/](https://primer.style/components/) to view documentation.
 
+_Note: This library is under active pre-1.0 development. Breaking changes are likely in patch releases._
+
 ## License
 
 The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).