docs: add changelog for Falcon v4 instrumentation

Author: stevapple

CHANGELOG.md

@@ -52,6 +52,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#3053](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3053))
 - `opentelemetry-instrumentation-sqlite3`: Update documentation on explicit cursor support of tracing
   ([#3088](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3088))
+- `opentelemetry-instrumentation-falcon`: expand supported version to v4
+  ([#3086](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3086))
 
 ### Breaking changes