Update ADK doc according to issue #1650 - 2

docs/integrations/parameter-manager.md

@@ -0,0 +1,40 @@
+---
+catalog_title: Parameter Manager
+catalog_description: A client for interacting with Google Cloud Parameter Manager.
+---
+
+# Parameter Manager
+
+The Parameter Manager integration provides a client for interacting with Google Cloud Parameter Manager.
+
+## Initialize the ParameterManagerClient
+
+You can initialize the `ParameterManagerClient` in a few ways:
+
+**Using default credentials**
+
+```python
+from google.adk.integrations.parameter_manager.parameter_client import ParameterManagerClient
+
+client = ParameterManagerClient()
+```
+
+**With a service account JSON string**
+
+```python
+client = ParameterManagerClient(service_account_json="...")
+```
+
+**With an auth token**
+
+```python
+client = ParameterManagerClient(auth_token="...")
+```
+
+## Retrieve a parameter
+
+To retrieve a parameter, use the `get_parameter` method with the full resource name of the parameter version:
+
+```python
+value = client.get_parameter("projects/my-project/locations/global/parameters/my-param/versions/latest")
+```