Add Danfoss wiring page link to CAN guide

docs/can-guide.md

@@ -10,8 +10,12 @@ Borrowing from [Wikipeda](https://en.wikipedia.org/wiki/CAN_bus):
 
 In simple terms, CAN is a way of communicating between many devices over a single twisted pair of wires.  The signal is transmitted as the difference in voltage between the two wires (differential signalling), which makes it very robust against noise.  Instead of using a unique address (like I2C) or a select pin (like SPI), CAN *messages* have a unique ID that also acts as the priority.  At the beginning of a message frame, all devices talk and read at the same time.  As the message ID is transmitted, the lowest value "wins" and that message will be transmitted (ID **0** has the *highest* priority).  All other devices will wait for the next chance to send.  If two devices send the same message ID at the same time, they will conflict and a bus failure may occur.  Make sure your devices can never send the same message ID at the same time!
 
+See also this great article from Danfoss that quickly describes how to put together the wiring for a CAN bus https://danfosseditron.zendesk.com/hc/en-gb/articles/360042232992-CAN-bus-physical-layer
+
 ![CAN picture](screenshots/CAN_Bus_Drawing.png)
 
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+
 ## Why use CAN?
 
 CAN is convenient for its simple and robust Physical Layer (PHY) that requires only a twisted pair of wires and a 120ohm termination resistor at each end.  It has low jitter and low latency, because there is no host computer.  It is relatively fast (CAN 2.0b supports 1 Mbps).  Messages are easy to configure and load with data.  Transceivers and controllers are inexpensive and widely available, thanks to its use in automotive.
@@ -131,4 +135,4 @@ Instead of manually writing values into the data, we can create a dictionary of
 
 The [CAN DBC Example](../tools/can_dbc_example.py) script shows you how this can be used.  This is the recommended method of serializing and deserializing.
 
-If you're using C++, then you can use the [CANHelpers](..firmware/communication/../../../Firmware/communication/can/can_helpers.hpp) single-header library to do this instead, although the DBC file isn't used.
+If you're using C++, then you can use the [CANHelpers](..firmware/communication/../../../Firmware/communication/can/can_helpers.hpp) single-header library to do this instead, although the DBC file isn't used.