say deriving abstract is not needed anymore

Author: tsnobip

pages/docs/manual/latest/generate-converters-accessors.mdx

@@ -9,6 +9,7 @@ canonical: "/docs/manual/latest/generate-converters-accessors"
 **Note**: if you're looking for:
 - `@deriving(jsConverter)` for records
 - `@deriving({jsConverter: newType})` for records
+- `@deriving(abstract)` for records
 - `@deriving(jsConverter)` for plain and polymorphic variants
 
 These particular ones are no longer needed. Select a doc version lower than `9.0` in the sidebar to see their old docs.