2020-11-18 CHANGELOG updates (#2092)
2020-11-18 CHANGELOG updates (#2092)

* add an item for the memory pool metrics fix.

* Update the CHANGELOG with unreleased changes.

* add a note for the change to TraceState validation

* Add an entry about the new proto-view implementation
open-telemetry/opentelemetry-java,open-telemetry/opentelemetry-java,open-telemetry/opentelemetry-java