Add info about new security checks

Author: emanuele-f

docs/app_api.md

@@ -94,6 +94,8 @@ As shown above, the capture settings can be specified by using intent extras. Th
 The `Ver` column indicates the minimum PCAPdroid version required to use the given parameter. The PCAPdroid version can be queried via the `get_status` action as explained below.
 The `Mode` column indicates if the option applies to any mode or only to the VPN or root mode.
 
+*NOTE*: for security reasons, since version 1.5.3 you cannot specify a remote server IP address in `collector_ip_address` or in `socks5_proxy_ip_address`. If you really want to do this, you should first set such a remote IP address via the PCAPdroid gui and only then invoke the API.
+
 *NOTE*: due to [file storage restrictions](https://developer.android.com/about/versions/11/privacy/storage), the `pcap_uri` must point to an app internal directory, e.g. `file:///data/user/0/com.emanuelef.remote_capture/cache/dump.pcap`.
 
 ## Query the Capture Status