LoRaMac-node version number in README.md is incorrect

[lnlp]

README.md states:

CubeCell series LoRaWAN-Node stack is migration form LoRaMac-node V4.4.0, based on "LoRaWAN specification 1.0.2" and "LoRaWAN Regional Parameters v1.0.2rB".

As previously noted in #51 the SX126x radio support was first added in V4.4.1. ASR650x uses SX1262 which was not yet supported in LoRaMac-node V4.4.0. The LoRaMac-node version V4.4.0 mentioned in README.md therefore has to be incorrect.

Please specify the correct LoRaMac-node version number so that people can check and compare with the LoRaMac-node revision history to see what new LoRaMac-node features have (not) been implemented and what issues have (not yet) been fixed in ASR650x-Arduino.

[Heltec-Aaron-Lee]

Hi, the LoRaMac-node version is based on V4.4.0, and added SX126x supported.