Added note about UDEV-rules on Arch

doc/Quickstart.md

@@ -42,6 +42,11 @@
 $ sudo pacman -Sy arm-none-eabi-{binutils,gdb} openocd
 ```
 
+For hardware-association and pre-packaged UDEV-rules also install:
+```
+$ sudo pacman -S stlink
+```
+
 ### macOS
 
 ``` console