documentation: add docstring for amtviz module

Author: Uemit Yoldas

src/sagemaker/amtviz/__init__.py

@@ -10,7 +10,16 @@
 # distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
 # ANY KIND, either express or implied. See the License for the specific
 # language governing permissions and limitations under the License.
-"""Placeholder docstring"""
+"""Amazon SageMaker Automatic Model Tuning Visualization module.
+
+This module provides visualization capabilities for SageMaker hyperparameter tuning jobs.
+It enables users to create interactive visualizations to analyze and understand the
+performance of hyperparameter optimization experiments.
+
+Example:
+    >>> from sagemaker.amtviz import visualize_tuning_job
+    >>> visualize_tuning_job('my-tuning-job')
+"""
 from __future__ import absolute_import
 
 from sagemaker.amtviz.visualization import visualize_tuning_job