[API.Context] Drop reference to binary propagator (open-telemetry#4490)

Author: Kielek

CHANGELOG.md

@@ -9,6 +9,9 @@ release.
 
 ### Context
 
+- Drop reference to binary `Propagator`.
+  ([#4490](https://github.com/open-telemetry/opentelemetry-specification/pull/4490))
+
 ### Traces
 
 ### Metrics

specification/context/api-propagators.md

@@ -70,8 +70,6 @@ The Propagators API currently defines one `Propagator` type:
 - `TextMapPropagator` is a type that injects values into and extracts values
   from carriers as string key/value pairs.
 
-A binary `Propagator` type will be added in the future (see [#437](https://github.com/open-telemetry/opentelemetry-specification/issues/437)).
-
 ### Carrier
 
 A carrier is the medium used by `Propagator`s to read values from and write values to.