add era units in Thai

cmd/resources/data/rules/th.yaml

@@ -74,6 +74,10 @@ datetime:
       medium: '{1}, {0}'
       short: '{1}, {0}'
   formatNames:
+    eras:
+      abbreviated:
+        ad: "\u0E04.\u0E28."
+        be: "\u0E1E.\u0E28."
     months:
       abbreviated:
         "1": "\u0E21.\u0E04."