Add two highlights

Author: seisman

doc/changes.md

@@ -6,16 +6,15 @@
 
 ### Highlights
 
-*
+* Patch release which allows passing None explicitly to pygmt functions ([#1872](https://github.com/GenericMappingTools/pygmt/pull/1872), [#1862](https://github.com/GenericMappingTools/pygmt/pull/1862), [#1857](https://github.com/GenericMappingTools/pygmt/pull/1857), [#1815](https://github.com/GenericMappingTools/pygmt/pull/1815))
+* A new tutorial for grdhisteq ([#1821](https://github.com/GenericMappingTools/pygmt/pull/1821))
 
 ### Bug Fixes
 
-* Allow passing None explicitly to pygmt functions ([#1872](https://github.com/GenericMappingTools/pygmt/pull/1872), [#1862](https://github.com/GenericMappingTools/pygmt/pull/1862), [#1857](https://github.com/GenericMappingTools/pygmt/pull/1857), [#1815](https://github.com/GenericMappingTools/pygmt/pull/1815))
 * Fix pathlib support for plot and plot3d ([#1831](https://github.com/GenericMappingTools/pygmt/pull/1831))
 
 ### Documentation
 
-* Add a tutorial for grdhisteq ([#1821](https://github.com/GenericMappingTools/pygmt/pull/1821))
 * Add inline example for grdvolume ([#1726](https://github.com/GenericMappingTools/pygmt/pull/1726))
 * Format author affiliations in CITATION.cff and AUTHORS.md ([#1844](https://github.com/GenericMappingTools/pygmt/pull/1844))