docs: add audit log export to S3 documentation

docs/my-website/docs/proxy/multiple_admins.md

@@ -56,6 +56,38 @@ On the LiteLLM UI, navigate to Logs -> Audit Logs. You should see the audit log
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+## Export Audit Logs to External Storage
+
+You can export audit logs to an external storage backend (e.g. S3) in addition to storing them in the database. Logs are batched and uploaded asynchronously, so they do not block your proxy requests.
+
+### S3 Example
+
+Add `audit_log_callbacks` and `s3_callback_params` to your `litellm_settings`:
+
+```yaml
+litellm_settings:
+  store_audit_logs: true
+  audit_log_callbacks: ["s3_v2"]
+  s3_callback_params:
+    s3_bucket_name: my-audit-logs-bucket     # AWS Bucket Name
+    s3_region_name: us-west-2                # AWS Region
+    s3_aws_access_key_id: os.environ/AWS_ACCESS_KEY_ID
+    s3_aws_secret_access_key: os.environ/AWS_SECRET_ACCESS_KEY
+    s3_path: litellm-audit                   # [OPTIONAL] prefix path in the bucket
+```
+
+Audit logs are written as JSON files to:
+
+```
+s3://<bucket>/<s3_path>/audit_logs/<YYYY-MM-DD>/<HH-MM-SS>_<audit-log-id>.json
+```
+
+:::info
+
+Both `store_audit_logs: true` and `audit_log_callbacks` must be set. If `store_audit_logs` is not enabled, the callbacks will not fire.
+
+:::
+
 ## Advanced
 
 ### Attribute Management changes to Users