feat: add udev instruction in readme

README.md

@@ -35,4 +35,30 @@ fbs run
 
 To run it for immediate use, just run `run.sh` and it'll set itself up and run.
 
+### UDEV
+
 Run with sudo to flash unless you have the correct udev rules set up.
+
+To setup the udev rule, run this command (tested for Berseker).
+
+```bash
+sudo bash -c 'cat << EOF > /etc/udev/rules.d/52-flash-keyboard.rules
+SUBSYSTEMS=="usb", ATTRS{idVendor}=="0c45", ATTRS{idProduct}=="7040", GROUP="users", MODE="0666"
+EOF'
+sudo systemctl restart udev
+```
+
+In order to check your bootloader's vendor & product IDs, run the following command, then immediately put your keyboard in bootloader mode, and wait for the diff.
+
+```
+lsusb > /tmp/pre; sleep 30; lsusb > /tmp/post; diff -u /tmp/pre /tmp/post
+```
+
+You should get something like this, look at the line starting with +.
+
+```
+[...]
+-Bus 003 Device 016: ID 320f:5042 GG Berserker
++Bus 003 Device 017: ID 0c45:7040 Microdia
+[...]
+```