docs: add new optional bigquery settings to documentation

Author: twishabansal

BIGQUERY.md

@@ -16,6 +16,10 @@ This section covers connecting to BigQuery.
 
  * `BIGQUERY_PROJECT`: The GCP project ID.
  * `BIGQUERY_LOCATION`: (Optional) Location of the BigQuery resources.
+ * `BIGQUERY_USE_CLIENT_OAUTH`: (Optional) Whether to use client OAuth (default: false).
+ * `BIGQUERY_SCOPES`: (Optional) Scopes for the BigQuery client.
+ * `BIGQUERY_MAX_QUERY_RESULT_ROWS`: (Optional) Maximum number of query result rows (default: 50).
+ * `BIGQUERY_IMPERSONATE_SERVICE_ACCOUNT`: (Optional) Service account to impersonate.
 
  If you need to update any of these values later, use the `gemini extensions config bigquery-data-analytics` command.
 
@@ -38,6 +42,10 @@ Users may have set project environment variables:
 
 * `BIGQUERY_PROJECT`: The GCP project ID.
 * `BIGQUERY_LOCATION`: (Optional) Location of the BigQuery resources.
+* `BIGQUERY_USE_CLIENT_OAUTH`: (Optional) Whether to use client OAuth (default: false).
+* `BIGQUERY_SCOPES`: (Optional) Scopes for the BigQuery client.
+* `BIGQUERY_MAX_QUERY_RESULT_ROWS`: (Optional) Maximum number of query result rows (default: 50).
+* `BIGQUERY_IMPERSONATE_SERVICE_ACCOUNT`: (Optional) Service account to impersonate.
 
 Instead of prompting the user for these values for specific skill calls, prompt the user to verify the reuse of a specific setting value.
 Make sure to not use the environment variable name like `BIGQUERY_PROJECT`, `${BIGQUERY_PROJECT}`, or `$BIGQUERY_PROJECT`. 

README.md

@@ -47,6 +47,10 @@ You will be prompted to configure the following settings during installation. Th
 
 *   `BIGQUERY_PROJECT`: The GCP project ID.
 *   `BIGQUERY_LOCATION`: (Optional) The dataset location.
+*   `BIGQUERY_USE_CLIENT_OAUTH`: (Optional) Whether to use client OAuth (default: false).
+*   `BIGQUERY_SCOPES`: (Optional) Scopes for the BigQuery client.
+*   `BIGQUERY_MAX_QUERY_RESULT_ROWS`: (Optional) Maximum number of query result rows (default: 50).
+*   `BIGQUERY_IMPERSONATE_SERVICE_ACCOUNT`: (Optional) Service account to impersonate.
 
 To view or update your configuration:
 
@@ -65,6 +69,10 @@ Alternatively, you can manually set these environment variables before starting
 ```bash
 export BIGQUERY_PROJECT="<your-gcp-project-id>"
 export BIGQUERY_LOCATION="<your-dataset-location>"  # Optional
+export BIGQUERY_USE_CLIENT_OAUTH="false"             # Optional
+export BIGQUERY_SCOPES=""                           # Optional
+export BIGQUERY_MAX_QUERY_RESULT_ROWS="50"           # Optional
+export BIGQUERY_IMPERSONATE_SERVICE_ACCOUNT=""       # Optional
 ```
 
 > [!NOTE]