update CHANGELOG

Author: matthewhanson

CHANGELOG.md

@@ -16,4 +16,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
-[Unreleased]: <https://github.com/stac-extensions/template/compare/v1.0.0...HEAD>
+## [v1.0.0] - 2021-03-08
+
+Initial independent release, see [previous history](https://github.com/radiantearth/stac-spec/commits/v1.0.0-rc.1/extensions/pointcloud)
+
+[Unreleased]: <https://github.com/stac-extensions/pointcloud/compare/v1.0.0...HEAD>
+[v1.0.0]: <https://github.com/stac-extensions/pointcloud/tree/v1.0.0>