DOCS: Update docs with latest findings

HARDWARE.md

@@ -18,7 +18,7 @@ Connect the RC522 RFID reader on the following ports:
 - RC522 PIN `2` / `SCK` ––– RPi PIN `23` / `SPI0 SCLK`
 - RC522 PIN `3` / `MOSI` ––– RPi PIN `19` / `SPI0 MOSI`
 - RC522 PIN `4` / `MISO` ––– RPi PIN `21` / `SPI0 MISO`
-- RC522 PIN `5` / `IRQ` ––– _do not connect_
+- RC522 PIN `5` / `IRQ` ––– RPi PIN `18` / `GPIO 24`
 - RC522 PIN `6` / `GND` ––– RPi PIN `20` / `GND`
-- RC522 PIN `7` / `RST` ––– RPi PIN `22`
+- RC522 PIN `7` / `RST` ––– RPi PIN `22` / `GPIO 25`
 - RC522 PIN `8` / `3.3V` ––– RPi PIN `17` / `3.3V PWR`

SETUP.md

@@ -99,7 +99,7 @@ Now prepare our Mopidy environment:
 
 ```
 groupadd -g 666 mopidy
-useradd -u 666 -g 666 -G audio -c "Mopidy User" -d /opt/mopidy -m -s /bin/bash mopidy
+useradd -u 666 -g 666 -G audio,spi,gpio -c "Mopidy User" -d /opt/mopidy -m -s /bin/bash mopidy
 ```
 
 Let's create our python venv and install mopidy:
@@ -149,4 +149,20 @@ After installing Iris, you might want to set the following settings:
 [iris]
 country = CH
 locale = de_CH
+```
+
+Pummeluff Extension
+-------------------
+
+The Pummeluff extension is in charge of the whole RFID handling. The sources for it reside in this repository, but we need to make sure we've all dependencies in place. Follow these steps to install it:
+
+```
+su - mopidy
+
+source mopidy/bin/activate
+
+pip install spidev      # Install this before pi-rc522
+pip install pi-rc522
+
+
 ```