Update ADK doc according to issue #1650 - 2

docs/integrations/parameter-manager.md

@@ -0,0 +1,51 @@
+---
+catalog_title: Parameter Manager
+catalog_description: A client for interacting with Google Cloud Parameter Manager.
+---
+
+# Parameter Manager
+
+You can use the `ParameterManagerClient` to securely fetch configuration and parameters from the Google Cloud Parameter Manager.
+
+## Initialize the client
+
+You can initialize the `ParameterManagerClient` in a few ways:
+
+### Using default credentials
+
+If you are running on a Google Cloud environment with default credentials, you can initialize the client without any arguments:
+
+```python
+from google.adk.integrations.parameter_manager.parameter_client import ParameterManagerClient
+
+# Using default credentials
+client = ParameterManagerClient()
+```
+
+### Using a service account
+
+You can provide a service account JSON string to authenticate:
+
+```python
+from google.adk.integrations.parameter_manager.parameter_client import ParameterManagerClient
+
+client = ParameterManagerClient(service_account_json="...")
+```
+
+### Using an auth token
+
+Alternatively, you can use an auth token:
+
+```python
+from google.adk.integrations.parameter_manager.parameter_client import ParameterManagerClient
+
+client = ParameterManagerClient(auth_token="...")
+```
+
+## Retrieve a parameter
+
+Once the client is initialized, you can retrieve a parameter by providing its full resource name:
+
+```python
+value = client.get_parameter("projects/my-project/locations/global/parameters/my-param/versions/latest")
+```