message: Update can_protocol docs with gain messages
diff: @@ -71,6 +71,8 @@ CMD ID | Name | Sender | Signals | Start byte | Signal Type | Bits | Factor | Of
  0x017 | Get Vbus Voltage | Master\*\*\* | Vbus Voltage | 0 | IEEE 754 Float | 32 | 1 | 0
  0x018 | Clear Errors | Master | - | - | - | - | - | -
  0x019 | Set Linear Count | Master | Position | 0 | Signed Int | 32 | 1 | 0
  +0x01A | Set Position Gain | Master | Pos Gain | 0 | IEEE 754 Float | 32 | 1 | 0
  +0x01B | Set Vel Gains | Master | Vel Gain<br>Vel Integrator Gain | 0<br>4 | IEEE 754 Float<br>IEEE 754 Float | 32<br>32 | 1<br>1 | 0<br>0
  0x700 | CANOpen Heartbeat Message\*\* | Slave | - | - | - | - | - | -
  -|-|-|----------------------------------|-|--------------------|-|-|-
  