This is the second release candidate of the 3.7 firmware line. It fixes issues found in rc.1. Upgrade notes and change list are at https://github.com/Duet3D/RepRapFirmware/wiki/Changelog-RRF-3.x-RC#reprapfirmware-370-rc2.
The P parameter of M955 and M956 is now mandatory, accelerometers have moved to sensors.accelerometers in the object model and the M23CL/TOOLINDX board temperature sensor now needs sensor type "board-temp", so please read the upgrade notes before installing.
The Wifi module firmware has not changed, current version is still 2.4.1.