Beta announcement

[Dirk Hohndel]

In the continuing story of "I am not spending enough time on Subsurface", I just 
managed to post the Subsurface beta announcement on our own website.

https://subsurface-divelog.org/2016/12/announcing-subsurface-4-6-beta-1/

Could someone review this for idiocities, typos and other mis-features, please?
I gotta run to a meeting, but I hope to post announcements to FB and G+ later
today.

Thanks

/D