maint: Add link to sunset issue in README (#245)

## Which problem is this PR solving?

Add link to sunset issue in README.

OSSMETADATA

@@ -1 +1 @@
-osslifecycle=maintained
+osslifecycle=beingsunset

README.md

@@ -1,9 +1,11 @@
 # Honeycomb Beeline for Ruby
 
-[![OSS Lifecycle](https://img.shields.io/osslifecycle/honeycombio/beeline-ruby?color=success)](https://github.com/honeycombio/home/blob/main/honeycomb-oss-lifecycle-and-practices.md)
+[![OSS Lifecycle](https://img.shields.io/osslifecycle/honeycombio/beeline-ruby?color=pink)](https://github.com/honeycombio/home/blob/main/honeycomb-oss-lifecycle-and-practices.md)
 [![Build Status](https://circleci.com/gh/honeycombio/beeline-ruby.svg?style=svg)](https://circleci.com/gh/honeycombio/beeline-ruby)
 [![Gem Version](https://badge.fury.io/rb/honeycomb-beeline.svg)](https://badge.fury.io/rb/honeycomb-beeline)
 
+⚠️**STATUS**: This project is being Sunset. See [this issue](https://github.com/honeycombio/beeline-ruby/issues/244) for more details.
+
 ⚠️**Note**: Beelines are Honeycomb's legacy instrumentation libraries. We embrace OpenTelemetry as the effective way to instrument applications. For any new observability efforts, we recommend [instrumenting with OpenTelemetry](https://docs.honeycomb.io/getting-data-in/opentelemetry/ruby/).
 
 This package makes it easy to instrument your Ruby web app to send useful events to [Honeycomb](https://www.honeycomb.io), a service for debugging your software in production.