[Docs] Missing "kubectl" in command

[kastl-ars]

https://github.com/microsoft/retina/blob/735192eb444bcf4413019c4fe68378b43e30299f/docs/04-Captures/cli.md?plain=1#L9

This should read kubectl retina capture....

[rbtr]

The Retina CLI can be invoked directly, it does not need to be kubectl plugin, so this would actually work. It is a bit confusing that all of the subsequent examples in this page invoke it as a plugin though. This should be explained and made consistent.

[kastl-ars]

Yes, it should be unified to make it consistent.

And: When I download the tarball from the release, there is only a kubectl-retina binary in it, without further instructions. Moving that to a directory in my PATH means I can call kubectl retina ..., but not retina directly.

As this is the only command without kubectl, I would propose to stick to the usage with kubectl retina ....