add proxy access log retention section (#693)

src/pages/manage/reverse-proxy/access-logs.mdx

@@ -84,6 +84,29 @@ Access logs support several operational and security workflows:
 - **Monitoring** - Track usage patterns across your services. Identify which services receive the most traffic, peak usage times, and unusual access patterns that may warrant investigation.
 - **Compliance** - Maintain records of service access for regulatory requirements. Access logs provide an auditable trail of who accessed what, when, and from where.
 
+## Retention and Cleanup
+
+For the cloud version of NetBird, access logs are retained for 7 days.
+For the self-hosted version, access log retention can be configured in the `management.json` or `config.yaml` by setting the following config parameters:
+
+```json
+{
+    "ReverseProxy": {
+        "AccessLogRetentionDays": 7,
+        "AccessLogCleanupIntervalHours": 24
+    }
+}
+```
+
+```yaml
+reverseProxy:
+  accessLogRetentionDays: 7
+  accessLogCleanupIntervalHours: 24
+```
+
+- **accessLogRetentionDays** - Define how long access logs are retained before they are automatically deleted.
+- **accessLogCleanupIntervalHours** - Set how often the system checks for and deletes expired access log entries.
+
 ## Related pages
 
 - [Reverse Proxy Overview](/manage/reverse-proxy) - learn how to create and manage reverse proxy services