Add archived status and recommend Headlamp

Added important notice about project status and alternatives.

Signed-off-by: Sebastian Florek <s.florek91@gmail.com>

Author: floreks

README.md

@@ -4,6 +4,15 @@
 [![Coverage Status](https://codecov.io/github/kubernetes/dashboard/coverage.svg?branch=master)](https://codecov.io/github/kubernetes/dashboard?branch=master)
 [![License](https://img.shields.io/badge/License-Apache%202.0-blue.svg)](https://github.com/kubernetes/dashboard/blob/master/LICENSE)
 
+## IMPORTANT
+
+**This project is now archived and no longer maintained due to lack of active maintainers and contributors.**
+
+Thank you to everyone who used, starred, or contributed to this project! Feel free to fork this repository if you want to continue development yourself.
+
+Please consider using **[Headlamp](https://github.com/kubernetes-sigs/headlamp)** instead. It was recently moved under the sig-ui. From the creators:
+> Headlamp is an easy-to-use and extensible Kubernetes web UI.
+
 ## Introduction
 
 Kubernetes Dashboard is a general purpose, web-based UI for Kubernetes clusters. It allows users to manage applications running in the cluster and troubleshoot them, as well as manage the cluster itself.