[Doc] Deprecate data_source_id attribute in databricks_sql_endpoint resource (#4929)

## Changes
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## Tests
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- [ ] `make test` run locally
- [x] relevant change in `docs/` folder
- [ ] covered with integration tests in `internal/acceptance`
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- [x] has entry in `NEXT_CHANGELOG.md` file

Author: alexott

NEXT_CHANGELOG.md

@@ -13,6 +13,7 @@
 ### Documentation
 
 * Document `email_notifications` block in model serving resources ([#4910](https://github.com/databricks/terraform-provider-databricks/pull/4910))
+* Deprecate `data_source_id` attribute in `databricks_sql_endpoint` resource ([#4929](https://github.com/databricks/terraform-provider-databricks/pull/4929))
 * Deprecate `databricks_sql_visualization` and `databricks_sql_widget` resource. ([#4924](https://github.com/databricks/terraform-provider-databricks/pull/4924))
 * Document `APPLY_TAG` privilege for `databricks_volume` grants ([#4928](https://github.com/databricks/terraform-provider-databricks/pull/4928))
 

docs/resources/sql_endpoint.md

@@ -55,7 +55,7 @@ In addition to all arguments above, the following attributes are exported:
 * `id` - the unique ID of the SQL warehouse.
 * `jdbc_url` - JDBC connection string.
 * `odbc_params` - ODBC connection params: `odbc_params.hostname`, `odbc_params.path`, `odbc_params.protocol`, and `odbc_params.port`.
-* `data_source_id` - ID of the data source for this endpoint. This is used to bind an Databricks SQL query to an endpoint.
+* `data_source_id` - (Deprecated) ID of the data source for this endpoint. This is used to bind an Databricks SQL query to an endpoint.
 * `creator_name` - The username of the user who created the endpoint.
 * `num_active_sessions` - The current number of clusters used by the endpoint.
 * `num_clusters` - The current number of clusters used by the endpoint.