Docs: Clarify guidance around quick start card label.

[edonehoo]

Follow-up to patternfly/chatbot#795

Make sure that it's clear that cards that initiate quick starts should use a nonstatus green label. Might be good to tackle this issue around the same time as updating all the docs images to use v6 styles: [ placeholder for link to an issue for this ]

[edonehoo]

I don't appear to have access to updating the properties of this issue, but this is something I can own and work on