Remove Qnap option in Quickstart

[germainelee]

Changelist:

• Remove Qnap option in https://owncast.online/quickstart/. You should see 2 options instead of 3 after Select "Other specific hardware or hosting environments".
• change Restart button color from light gray to purple as gray button gives the disabled/non-interactable look

closes owncast/owncast#4234
links to owncast/owncast#4233

[gabek]

It might be worth only making changes on the new version of the web site going forward. While it won't help the current version of the site, once we get there, all of these problems will come back.

[germainelee]

I thought it would be easier if I make changes on the current documentation site so that the changes would be reflected on the new one when migrated.