sendCommand url fix for Tasmota 12.1.1

[kajarit]

current code:
url = str("http://{}/ax?c2=191&c1=RfRaw%20".format(mydevice))
working for me:
url = str("http://{}/cm?cmnd=RfRaw%20".format(mydevice))

[kajarit]

This PR seems similar:

#9 fixed http command and readme