Merge pull request 'docs: improve zerotier documentation' (#1992) from kenji/clan-core:improve-zerotier-setup into main

docs/site/getting-started/mesh-vpn.md

@@ -58,7 +58,18 @@ To introduce a new machine to the VPN, adhere to the following steps:
    Replace `<NEW_MACHINE>` with the designated new machine name.
 
     !!! Note "For Private Networks"
-        1. **Retrieve the ZeroTier ID**: On the `new_machine`, execute:
+        1. **Retrieve Zerotier Metadata**
+
+            === "From the repo"
+                **Retrieve the ZeroTier IP**: In the clan repo, execute:
+                 ```console
+                 $ clan facts list <NEW_MACHINE> |  jq -r '.["zerotier-ip"]'
+                 ```
+
+                 The returned address is the Zerotier IP address of the machine.
+
+            === "On the new machine"
+                **Retrieve the ZeroTier ID**: On the `new_machine`, execute:
                  ```bash
                  $ sudo zerotier-cli info
                  ```
@@ -67,8 +78,17 @@ To introduce a new machine to the VPN, adhere to the following steps:
                  200 info d2c71971db 1.12.1 OFFLINE
                  ```
                  , where `d2c71971db` is the ZeroTier ID.
+
+          
         2. **Authorize the New Machine on the Controller**: On the controller machine,
              execute:
+
+            === "with ZerotierIP"
+                 ```bash
+                 $ sudo zerotier-members allow --member-ip <IP>
+                 ```
+                 Substitute `<IP>` with the ZeroTier IP obtained previously.
+            === "with ZerotierID"
                  ```bash
                  $ sudo zerotier-members allow <ID>
                  ```