Add link to our GitHub organization

[WasabiFan]

From ev3dev/ev3dev#734.

[vinicentus]

Maybe there could be a like somewhere in the header?

[WasabiFan]

Yeah, that might be where I put it. I haven't started on this yet so I don't know exactly where it will go.

[WasabiFan]

Another part of this task is to invite people to look at and contribute to the website repo. I think that people generally don't notice that this repository exists, so a means of getting people here who may want to help would be nice.