stable grid readme edits

stable-crust/grid/README.md

@@ -61,3 +61,10 @@ should be the same as for 2014.
 | SSCn  | Paleozoic [7]         | adapt | 8037 |
 | SSCn  | Paleozoic [8]         | adapt | 8038 |
 | SSCn  | default               | adapt | 8039 |
+
+## 2023 Updates
+
+ - Multiple declustering methods considered (gk, nn, r85)
+ - Adaptive/fixed smoothing weights changed from 40/60 to 50/50, consistent with `active-crust`
+ - rates being used in model are total catalog rates, not declustered rates.
+ - TODO update 2023 ID's