Getting rid of alpha label

[Pjotr Prins]

Can we get rid of the alpha status? It suggests packages are in alpha,
which they are not. 

I have already had two different administrators in two environments
claiming that Guix packages can not be deployed on HPC systems because
it is alpha. 

The excuse is too easy ;)

I think GuixSD should be alpha. But it should not be proclaimed on the
main website. Sure there are bugs to be ironed out, but we are
actually better than Debian for the packages that we have.

Pj.