[luau] linux service descriptions wiki page

[David Burns]

> Seriously, this is good.  We should all show the
same initiative.

Aw shucks, I had to write it down for myself, might as
well put it where other people might find it.

I've added Warren's correction about sgi_fam. I feel I
ought to scold him a bit, it's just as easy to update
the wiki as it is to send in an email to luau. I guess
it's just the kindergarten teacher hidden in me
struggling to get out.

TB