Update FAQ with settings used for Apple Music's "High Efficiency" quality

[kylagit]

Apple Music has a quality mode called "High Efficiency" which uses HE-AAC at 64kbps, however the bitrate control method (CBR/ABR/CVBR/TVBR) and the quality (encoding speed) setting are not mentioned. It would be good to see the settings used for that added to the QAAC FAQ.

I have also heard that Apple has switched from CVBR to TVBR for the 256kbps LC-AAC (iTunes Plus) setting. If you can confirm that this is correct then it would be good to update the FAQ to also reflect this.