change Agile Labor Categories to a redirect

There's consensus to kill off this site - https://agile-labor-categories.18f.gov.  

It'd be good to first redirect the site to https://agile.18f.gov/ for a 6 months or so.  I know that the DNS for this is [here](https://github.com/18F/dns/blob/main/terraform/18f.gov.tf#L116-L126), but am uncomfortable proposing the code-level change for that file.  Is anyone else here game to create the PR?  






