docs: clarify new repo, port-forward flags (#6937)
docs: clarify new repo, port-forward flags (#6937)

The instructions for telling the CLI how to automatically use
port-forward were intertwined with the instructions for registering a
repo; this separates them.

This also moves the port-forward flags instructions to the first place
in the doc a user would need them.

Signed-off-by: Josh Gavant <636a22aa49a29071b173f9ea8c4e2e0bcda63673@gmail.com>
argoproj/argo-cd,argoproj/argo-cd,argoproj/argo-cd,argoproj/argo-cd,argoproj/argo-cd