Changelog updated for release

CHANGELOG.md

@@ -4,15 +4,15 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [Unreleased]
+## 2021-03-15 - version 0.4.1
 
 ### Changed
 - `get_grid_beam_directions` default meshing changed to "spherified_cube_edge" from "spherified_cube_corner"
 
 ### Fixed
 - `get_grid_beam_directions` now behaves correctly for the triclinic and monoclinic cases
-- 
-## 2020-01-11 - version 0.4.0
+
+## 2021-01-11 - version 0.4.0
 ### Changed
 - `get_grid_beam_directions`, now works based off of meshes
 - the arguments in the `DiffractionGenerator` constructor and the `DiffractionLibraryGenerator.get_diffraction_library` function have been shuffled so that the former captures arguments related to "the instrument/physics" while the latter captures arguments relevant to "the sample/material".