Add few words on MIDI Ports

[hypercube-software]

Hello there, thanks for those insights, I will certainly build a real editor with a nice GUI someday
anyway, as a side note, it would be nice to add the following:

for the MPK261 there are 4 MIDI IN/OUT ports

• sysex can be send on MIDI OUT port 1,2 and 4, not 3 !
• sysex can be received only on MIDI IN port 4

Port 1: MIDI Port A 1-16
Port 2: MIDI Port B 1-16
Port 3: Used to Send/Receive from the physical DIN5 MIDI ports on the back of the MPK2
Port 4: Send/Receive SYSEX