Add release notes.

Author: samuel-williams-shopify

releases.md

@@ -1,3 +1,20 @@
 # Releases
 
 ## Unreleased
+
+### New Context Propagation Interface
+
+This release adds comprehensive support for OpenTelemetry's context propagation system, enabling efficient inter-process and intra-process tracing with full W3C compliance.
+
+  - `Traces.current_context` - Capture the current trace context for local propagation between execution contexts (threads, fibers).
+  - `Traces.with_context(context)` - Execute code within a specific trace context, with automatic restoration when used with blocks.
+  - `Traces.inject(headers = nil, context = nil)` - Inject W3C Trace Context and Baggage headers into a headers hash for distributed propagation.
+  - `Traces.extract(headers)` - Extract trace context from W3C Trace Context headers.
+
+## v0.2.0
+
+  - Prefer to use `Tracer#in_span`.
+
+## v0.1.0
+
+  - Complete implementation of traces backend for OpenTelemetry.