doc: add SQL ALTER fro extra to JSONB type to NEWS

Author: sebix

NEWS.md

@@ -24,6 +24,11 @@ Please refer to the change log for a full list of changes.
 ### Libraries
 
 ### Postgres databases
+To switch to the more efficient data type `jsonb` instead of `json`, use the following SQL statement. Data is preserved. JSONB also has more query and data manipulation features than plain JSON.
+```sql
+ALTER TABLE events
+   ALTER COLUMN "extra" SET DATA TYPE jsonb;
+```
 
 
 3.4.0 Feature release (2025-03-14)