message: Add section on cyclic messages to can_protocol
diff: @@ -84,6 +84,18 @@ All multibyte values are little endian (aka Intel format, aka least significant
  ---
  +### Cyclic Messages
  +Cyclic messages are sent by ODrive on a timer without a request. As of `fw0.5.4`, the Cyclic messsages are:
  +
  +ID | Name | Rate (ms)
  +--: | :-- | :--
  +0x001 | ODrive Heartbeat Message | 100
  +0x009 | Encoder Estimates | 10
  +
  +These can be configured for each axis, see e.g. `axis.config.can`.
  +
  +---
  +
  ### Interoperability with CANopen
  You can deconflict with CANopen like this:
  