Access home network add subnet section (#396)

* Update access-home-network.mdx

Create a rough draft for finding subnet

* clean up spacing, change section wording

Author: SunsetDrifter

src/pages/how-to/access-home-network.mdx

@@ -39,6 +39,57 @@ After the registration is complete, proceed to the [**NetBird dashboard**](https
     <img src="/docs-static/img/how-to-guides/access-home-network/add-network-home-lan.png" alt="add-network-home-lan" className="imagewrapper"/>
 </p>
 
+## Identify Your Local Subnet
+Use the steps below to quickly identify your local subnet for use as a Network Resource.
+### Windows
+1. Open **Command Prompt**.
+2. Run:
+   ```bash
+   ipconfig
+   ```
+3. Look for your active network adapter.
+4. Note the values for:
+   - `IPv4 Address`
+   - `Subnet Mask`
+   Example:
+   ```
+   IPv4 Address. . . . . . . . . . . : 192.168.1.10
+   Subnet Mask  . . . . . . . . . . : 255.255.255.0
+   ```
+   The subnet is `192.168.1.0/24`.
+### Linux
+1. Open **Terminal**.
+2. Run:
+   ```bash
+   ip -c a
+   ```
+   or
+   ```bash
+   ip route
+   ```
+3. Identify the active interface (e.g., `eth0`, `wlan0`) and note the IP with CIDR suffix:
+   Example:
+   ```
+   inet 192.168.1.10/24
+   ```
+   The subnet is `192.168.1.0/24`.
+### macOS
+1. Open **Terminal**.
+2. Run:
+   ```bash
+   ifconfig
+   ```
+3. Locate the active interface (`en0`, `en1`, etc.).
+4. Look for:
+   - `inet` (IP address)
+   - `netmask` (in hex)
+   Example:
+   ```
+   inet 192.168.1.10 netmask 0xffffff00
+   ```
+   Hex `0xffffff00` = `255.255.255.0`, which is `/24`.
+   The subnet is `192.168.1.0/24`.
+
 ## Define Your LAN as a Network Resource
 1. Click **Add Resource**.
 2. Enter a name like "Home Subnet" and the CIDR of your home network into the Address field (e.g., 192.168.1.0/24).
@@ -112,4 +163,4 @@ you've previously created.
 2. A successful ping response confirms that your routing peer is correctly routing traffic to resources in your home network.
 
 That’s it! You’ve successfully mapped your entire home LAN into a NetBird Network. Any peer included in your access policy
-can now securely access resources in your home subnet via your designated routing peer, without the need to open router ports or install software on every device.
+can now securely access resources in your home subnet via your designated routing peer, without the need to open router ports or install software on every device.