Add instructions for assigning and enabling the NetBird interface in pfSense (#411)

Signed-off-by: bcmmbaga <bethuelmbaga12@gmail.com>

src/pages/how-to/installation/pfsense.mdx

@@ -69,6 +69,44 @@ Use this section for diagnostics and troubleshooting common connection or setup
     <img src="/docs-static/img/how-to-guides/pfSense/status.png" alt="connection status" className="imagewrapper-big"/>
 </p>
 
+### Assign NetBird interface
+After authentication, a new interface named `wt0(wt0)` will be available but unassigned. To assign it go to
+`Interfaces` > `Assignments`. Under `Available network ports`, select the NetBird interface `wt0(wt0)` and click `Add`.
+
+<p>
+    <img src="/docs-static/img/how-to-guides/pfSense/new_interface.png" alt="NewInterface" className="imagewrapper-big"/>
+</p>
+
+### Enable the NetBird interface
+
+Now that the NetBird interface has been added, you need to enable it. Go to `Interfaces` > `OPT1`, then configure
+the following options and click `Save`, then `Apply changes` to activate the interface:
+
+- **Enable**: `✓ Enable Interface`
+- **Description**: `NetBird`
+
+<p> <img src="/docs-static/img/how-to-guides/pfSense/enable_interface.png" alt="enableInterface" className="imagewrapper-big"/> </p>
+
+### Configure Firewall Rules for the NetBird interface
+
+To allow NetBird to handle all access control, permit all traffic on the NetBird interface in pfSense. This ensures traffic
+flows freely, while NetBird’s own policies (ACLs) govern the access restrictions.
+
+Create rules to control traffic coming from your NetBird network into pfSense and your local networks:
+
+1. Go to `Firewall` > `Rules` and select the `NetBird` (interface) tab and click `Add` to create rules
+2. Configure the rule:
+    - **Action**: `Pass`
+    - **Interface**: `NETBIRD`
+    - **Address Family**: `in`
+    - **Protocol**: `Any`
+    - **Source**: `Any`
+    - **Destination**: `Any`
+    - **Description**: `Allow all on NetBird (managed by NetBird)`
+3. Click `Save`, then `Apply Changes`
+
+<p><img src="/docs-static/img/how-to-guides/pfSense/firewall_rules.png" alt="firewallRules" className="imagewrapper-big"/></p>
+
 ## Uninstallation
 
 From a shell on your pfSense system, run: