Add links to latest stable version for items in 3_installation/Software-Check.md installed w wget or curl

In 3_installation/Software-Check.md kubectl, terraform, flux cli, and sops are installed with wget or curl, so out of necessity the instructions specify a version. The latest stable version should actually be installed so I want to include links to where to find it for each of these.

kubectl: https://kubernetes.io/releases/

Terraform: https://releases.hashicorp.com/terraform

Flux CLI: https://github.com/fluxcd/flux2/releases

sops: https://github.com/getsops/sops/releases