docs: Update transport docstrings to include that REST is in preview

PiperOrigin-RevId: 611222651

Author: matthew29tang

google/cloud/aiplatform/initializer.py

@@ -182,7 +182,9 @@ def init(
                 Optional. The desired API endpoint,
                 e.g., us-central1-aiplatform.googleapis.com
             api_transport (str):
-                Optional. The transport method which is either 'grpc' or 'rest'
+                Optional. The transport method which is either 'grpc' or 'rest'.
+                NOTE: "rest" transport functionality is currently in a
+                beta state (preview).
         Raises:
             ValueError:
                 If experiment_description is provided but experiment is not.

google/cloud/aiplatform/utils/__init__.py

@@ -403,6 +403,8 @@ def __init__(
                     Optional. Client credentials to pass to client.
                 transport (str):
                     Optional. Transport type to pass to client.
+                    NOTE: "rest" transport functionality is currently in a
+                    beta state (preview).
             """
 
             self._client_class = client_class
@@ -472,6 +474,8 @@ def __init__(
                 Optional. Client credentials to pass to client.
             transport (str):
                 Optional. Transport type to pass to client.
+                NOTE: "rest" transport functionality is currently in a
+                beta state (preview).
         """
         kwargs = dict(
             credentials=credentials,