Updated credentials docs "Added section Destination configuration via Python"

docs/website/docs/general-usage/credentials/advanced.md

@@ -160,6 +160,31 @@ dlt.secrets["destination.postgres.credentials"] = BaseHook.get_connection('postg
 
 This will mock the TOML provider to desired values.
 
+## Configuring destination credentials in code
+
+If you need to manage destination credentials programmatically, such as retrieving them from environment variables, you can define them directly in your pipeline code.
+
+The following example demonstrates how to use [GcpServiceAccountCredentials](complex_types#gcp-credentials) to set up a pipeline with a BigQuery destination.
+
+```py
+import os
+
+import dlt
+from dlt.sources.credentials import GcpServiceAccountCredentials
+from dlt.destinations import bigquery
+
+# Retrieve credentials from the environment variable
+creds_dict = os.getenv('BIGQUERY_CREDENTIALS')
+
+# Create credentials instance and parse them from a native representation
+gcp_credentials = GcpServiceAccountCredentials()
+gcp_credentials.parse_native_representation(creds_dict)
+
+# Pass the credentials to the BigQuery destination
+pipeline = dlt.pipeline(destination=bigquery(credentials=gcp_credentials))
+pipeline.run([{"key1": "value1"}], table_name="temp")
+```
+
 ## Example
 
 In the example below, the `google_sheets` source function is used to read selected tabs from Google Sheets.
@@ -200,5 +225,4 @@ In the example above:
 :::tip
 `dlt.resource` behaves in the same way, so if you have a [standalone resource](../resource.md#declare-a-standalone-resource) (one that is not an inner function
 of a **source**)
-:::
-
+:::