Updated the readme to add a comment about udev rules

Author: magicmonkey

README.md

@@ -21,6 +21,14 @@ Either include the library in your project or install it with the following comm
 go get github.com/magicmonkey/go-streamdeck
 ```
 
+On Linux, you might also need to add some `udev` rules (this assumes there's a `plugdev` group, like on Debian-based systems, feel free to amend the group to something more appropriate for your system).  Put this into `/etc/udev/rules.d/99-streamdeck.rules`:
+```
+SUBSYSTEM=="usb", ATTRS{idVendor}=="0fd9", ATTRS{idProduct}=="0060", MODE:="666", GROUP="plugdev"
+SUBSYSTEM=="usb", ATTRS{idVendor}=="0fd9", ATTRS{idProduct}=="0063", MODE:="666", GROUP="plugdev"
+SUBSYSTEM=="usb", ATTRS{idVendor}=="0fd9", ATTRS{idProduct}=="006c", MODE:="666", GROUP="plugdev"
+SUBSYSTEM=="usb", ATTRS{idVendor}=="0fd9", ATTRS{idProduct}=="006d", MODE:="666", GROUP="plugdev"
+```
+
 ## Usage
 
 There are 2 ways to use this: the low-level "comms-oriented" interface (using `streamdeck.Open`) which wraps the USB HID protocol, or the higher-level "button-oriented" interface (using `streamdeck.New`) which represents buttons and actions.