docs: add RTL8812BU driver install to deploy guide

Co-authored-by: Copilot <[email protected]>

deploy/readme.md

@@ -40,6 +40,32 @@ sudo systemctl status yaris-netwatch.timer --no-pager
 curl -I http://127.0.0.1/
 ```
 
+## TP-Link Archer T3U (RTL8812BU) driver
+
+This project expects the T3U USB adapter as `wlan1` for hotspot/uplink logic.
+On a fresh Pi, install the RTL8812BU DKMS driver before configuring WiFi
+profiles:
+
+```bash
+sudo apt-get update
+sudo apt-get install -y git dkms build-essential bc raspberrypi-kernel-headers
+cd /tmp
+git clone https://github.com/morrownr/88x2bu-20210702.git
+cd 88x2bu-20210702
+sudo ./install-driver.sh
+sudo reboot
+```
+
+After reboot, verify:
+
+```bash
+ip link show wlan1
+```
+
+If `wlan1` is still missing, do not continue with `ifname wlan1` profiles yet.
+Either fix the driver first, or temporarily use `wlan0` and update `WLAN`/`WLAN_FB`
+in `deploy/install_netwatch.sh`.
+
 ## 1) Base OS and assumptions
 
 - Raspberry Pi OS Bookworm (Lite is fine)