Update quick-start.md to use kubeless namespace

[jorijinnall]

You ask at the beggining to create the namespace kubeless, but then it is not used at all.
That makes me some confusion, I advise to use it everywhere

Issue Ref: #1005

Description: Should use kubeless namespace everywhere

[PR Description]

TODOs:

• [x ] Ready to review
• Automated Tests
• [ x] Docs

[andresmgot]

Hi @jorijinnall,

The kubeless namespace is used at the very beginning. Kubeless controllers are installed, by default, in that namespace. That's why you need to create it beforehand. You can check that the Kubeless controller is there if you execute kubectl get pods -n kubeless.

For the rest of the guide, I'd rather use the default namespace since the commands are simpler and easier to understand.

Thank you for your suggestion! I hope it's more clear now.