fixup! fixup! fixup! docs: make clearer the c8y-remote-access-plugin requirements

Signed-off-by: Didier Wenzek <didier.wenzek@free.fr>

Author: didier-wenzek

docs/src/operate/c8y/remote-access.md

@@ -11,6 +11,11 @@ import BrowserWindow from '@site/src/components/BrowserWindow';
 You can use the remote access feature of Cumulocity to access via SSH or VNC a device that runs %%te%%,
 without having to expose the SSH or VNC service over a public IP address.
 
+In its simplest form, the Cumulocity Remote Access feature allows you to open a shell session on the device from you tenant.
+However, combined with `PASSTHROUGH` option, this feature is extremely versatile
+and allows arbitrary TCP connections between a client on your local machine and a service on the device
+(such as the SSH daemon/service, or a local HTTP server).
+
 When a cloud remote access operation is received by the `tedge-mapper-c8y`,
 a process is spawned to establish a direct communication to Cumulocity.
 That connection being independent of any local services,
@@ -80,3 +85,11 @@ the `c8y-remote-access-plugin` must be running as a socket activated service:
 </BrowserWindow>
 
 :::
+
+## PASSTHROUGH
+
+To enable the `PASSTHROUGH` option of Cumulocity Remote Access, nothing specific has to be done on the %%te%% device,
+beyond enabling the `c8y-remote-access-plugin`. This option has only to be enabled on your tenant when configuring remote access.
+
+However, you will have to configure your local machine to fully leverage the `PASSTHROUGH` option.
+For that, the recommendation is to use the [`go-c8y-cli` remoteaccess](https://c8y.app/docs/examples/remoteaccess/) command.