add UPDATING note and improve description

UPDATING.md

@@ -78,6 +78,8 @@ assists people when migrating to a new version.
 
 ### Other
 
+- [24982](https://github.com/apache/superset/pull/24982): By default, physical datasets on Oracle-like dialects like Snowflake will now use denormalized column names. However, existing datasets won't be affected. To change this behavior, the "Advanced" section on the dataset modal has a "Normalize column names" flag which can be changed to change this behavior.
+
 ## 2.1.0
 
 - [22809](https://github.com/apache/superset/pull/22809): Migrated endpoint `/superset/sql_json` and `/superset/results/` to `/api/v1/sqllab/execute/` and `/api/v1/sqllab/results/` respectively. Corresponding permissions are `can sql_json on Superset` to `can execute on SQLLab`, `can results on Superset` to `can results on SQLLab`. Make sure you add/replace the necessary permissions on any custom roles you may have.

superset-frontend/src/components/Datasource/DatasourceEditor.jsx

@@ -999,7 +999,7 @@ class DatasourceEditor extends React.PureComponent {
  fieldKey="normalize_columns"
  label={t('Normalize column names')}
  description={t(
- 'Allow column names to be changed to case insensitive format',
+ 'Allow column names to be changed to case insensitive format, if supported (e.g. Oracle, Snowflake).',
  )}
  control={<CheckboxControl controlId="normalize_columns" />}
  />

superset/connectors/sqla/views.py

@@ -381,7 +381,8 @@ class TableModelView( # pylint: disable=too-many-ancestors
  True,
  ),
  "normalize_columns": _(
- "Allow column names to be changed to case insensitive format"
+ "Allow column names to be changed to case insensitive format, "
+ "if supported (e.g. Oracle, Snowflake)."
  ),
  }
  label_columns = {