update changelog

Author: nizartaha

CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 * Added `Plane.offset`
+* Added `is_mesh_closed` property to `compas.datastructures.mesh_slice_plane`
 ### Added
 
 * Added `draw_vertexlabels`, `draw_edgelabels`, `draw_facelabels`, `draw_vertexnormals`, and `draw_facenormals` to `compas_blender.artists.MeshArtist`.