Add changelog entry for added dg/rl cmake targets.

CHANGELOG.md

@@ -16,6 +16,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Information about the depth of the reference surface in the PointDistanceFromCurvedPlanes structure. \[Menno Fraters; 2021-07-20; [#320](github.com/GeodynamicWorldBuilder/WorldBuilder/pull/320)\]
 - The option for a smooth slab temperature structure that conserves mass with distance along the slab surface. \[Magali Billen; 2021-07-28; [#323](github.com/GeodynamicWorldBuilder/WorldBuilder/pull/323)\]
 - The option for a temperature model for an oceanic plate with a constant age using the plate model. \[Haoyuan Li; 2021-10-29; [#344](https://github.com/GeodynamicWorldBuilder/WorldBuilder/pull/344)\]
+- The cmake targets to easily switch between debug and release mode \[Menno Fraters; 2021-10-31; [#361](https://github.com/GeodynamicWorldBuilder/WorldBuilder/pull/361)\]
 
 ### Changed
 - The World Builder Visualizer will now use zlib compression for vtu files by default. If zlib is not available binary output will be used. \[Menno Fraters; 2021-06-26; [#282](github.com/GeodynamicWorldBuilder/WorldBuilder/pull/282)\]