NEWS.md: retroactively add release notes

Problem: there are no release notes for prior flux-coral2
releases.

Add them.

Author: jameshcorbett

NEWS.md

@@ -1,4 +1,23 @@
+flux-coral2 0.3.0 - 2023-01-31
+------------------------------
+
+Initial release of DWS/Rabbit plugins.
+
+
+flux-coral2 0.2.0 - 2022-10-12
+------------------------------
+
+Fixes for Cray MPI plugins
+
+
+
+flux-coral2 0.1.0 - 2022-08-18
+------------------------------
+
+Initial release of Cray MPI plugins
+
+
 flux-coral2 0.0.0 - 2021-04-14
 ------------------------------
 
-Inital release - for building and testing only
+Inital release - for building and testing only