docs: preserve existing kernel comment

Author: vuanhphung

src/databricks/sql/client.py

@@ -119,11 +119,17 @@ def __init__(
                 the Thrift backend.
             :param use_kernel: `bool`, optional (default is False)
                 Route the connection through the Rust kernel
-                (``databricks-sql-kernel`` via PyO3). Install the
-                connector's ``kernel`` extra to include the extension.
-                Supports PAT, OAuth M2M/U2M, and workload identity
-                federation; custom credentials providers are not
-                supported. Mutually exclusive with ``use_sea``.
+                (``databricks-sql-kernel`` via PyO3). Requires the
+                kernel extension to be installed separately — the
+                wheel is not yet published on PyPI, so today the
+                only supported install path is a local
+                ``maturin develop --release`` build from the
+                ``databricks-sql-kernel`` repo into the same venv.
+                Raises ``ImportError`` if the extension is not
+                available. In active development — PAT auth only
+                today; OAuth / federation / external credentials
+                and native parameter binding land in follow-ups.
+                Mutually exclusive with ``use_sea``.
             :param use_hybrid_disposition: `bool`, optional (default is False)
                 Use the hybrid disposition instead of the inline disposition.
             :param server_hostname: Databricks instance host name.