add jsonb in postgresql

docs/fields/field-types.md

@@ -140,6 +140,13 @@ You can pass `timezone=True` for timezone aware database column.
 * Sqlalchemy column: `sqlalchemy.JSON`  
 * Type (used for pydantic): `pydantic.Json` 
 
+### JSONB
+
+`JSONB()` has no required parameters, only support it in the postgresql.
+
+* Sqlalchemy column: `sqlalchemy.dialects.postgresql.JSONB`  
+* Type (used for pydantic): `pydantic.Json` 
+
 ### LargeBinary
 
 `LargeBinary(max_length)` has a required `max_length` parameter.