Merge pull request #52 from klinquist/bootloader-mode-photo

Include photo of shorted pins, add sudo note

README.md

@@ -91,12 +91,14 @@ For building the firmware, clone the repository and initialize the submodules. C
 ### Initial programming
 The following steps are required for initial programming of the AIOC:
 - Short outermost pins on the programming header. This will set the device into bootloader mode in the next step.
+![Shorting pins for bootloader mode](doc/images/k1-aioc-dfu.jpg?raw=true "Shorting pins for bootloader mode")
 - Connect USB-C cable to the AIOC PCB
 - Use a tool like ``dfu-util`` to program the firmware binary from the GitHub Releases page like this:
   ````
   dfu-util -a 0 -s 0x08000000 -D aioc-fw-x-y-z.bin
   ````
   __Note__ that a ``libusb`` driver is required for this. On Windows there are additional steps required as shown [here](https://yeswolf.github.io/dfu) (*DFuSe Utility and dfu-util*). On other operating systems (e.g. Linux, MacOS), this just works ™ (provided libusb is installed on your system).
+  On Linux (and MacOS), your user either needs to have the permission to use libusb (``plugdev`` group) or you might need to use ``sudo``.
 - Remove short from first step, unplug and replug the device, it should now enumerate as the AIOC device
 
 ### Firmware updating