Update CHANGELOG for 0.3.0 (#481)

Author: carlosalberto

CHANGELOG.md

@@ -7,6 +7,29 @@ the release.
 
 ## Unreleased
 
+## v0.3.0 (02-21-2020)
+
+- [OTEP-0059](https://github.com/open-telemetry/oteps/blob/master/text/0059-otlp-trace-data-format.md) Add OTLP Trace Data Format specification.
+- [OTEP-0066](https://github.com/open-telemetry/oteps/blob/master/text/0066-separate-context-propagation.md) Separate Layer for Context Propagation.
+- [OTEP-0070](https://github.com/open-telemetry/oteps/blob/master/text/0070-metric-bound-instrument.md) Rename metric instrument "Handles" to "Bound Instruments".
+- [OTEP-0072](https://github.com/open-telemetry/oteps/blob/master/text/0072-metric-observer.md) Metric Observer instrument specification (refinement).
+- [OTEP-0080](https://github.com/open-telemetry/oteps/blob/master/text/0080-remove-metric-gauge.md) Remove the Metric Gauge instrument, recommend use of other instruments.
+- Update 0003-measure-metric-type to match current Specification.
+- Update 0009-metric-handles to match current Specification.
+- Clarify named tracers and meters.
+- Remove SamplingHint from the Sampling OTEP (OTEP-0006).
+- Remove component attribute.
+- Allow non-string Resource label values.
+- Allow array values for attributes.
+- Add service version to Resource attributes.
+- Add general, general identity, network and VM image attribute conventions.
+- Add a section on transformation to Zipkin Spans.
+- Add a section on SDK default configuration.
+- Enhance semantic conventions for HTTP/RPC.
+- Provide guidelines for low-cardinality span names.
+- SDK Tracer: Replace TracerFactory with TracerProvider.
+- Update Resource to be in the SDK.
+
 ## v0.2.0 (10-22-2019)
 
 - [OTEP-0001](https://github.com/open-telemetry/oteps/blob/master/text/0001-telemetry-without-manual-instrumentation.md) Added Auto-Instrumentation.