Task: update the "Postpone" part

### Describe what issue or improvement you have with the usability design

I would like to re-do the "Postpone" part. Make clear what it does. Does it pause the app/svc or delay the switch?

### Describe how you would like to see it improved

More text, and headers for controls.
Add link to wiki.

### Additional context

> This is what Postpone does:
>
> Postpone delays theme switches by x hours or once (one entire day).
Personally I would say, the user does not care about pausing or delaying, because for the user its kinda the same.
Active delays are a collection of delays reported by the backend's postpone system (e.g if switching is delayed due to GPU usage, or an active program, or mouse activity)
The delay button may either set a user-configurable postpone delay, or clear it, but does not remove non-user set postpones.

~ Armin

No file or test is named. Start by locating the Postpone controls in the Windows desktop UI and review the wiki material referenced by the issue. Done means the UI explains user-configurable postpones and active backend delays, uses headers for controls, provides more text, and includes a wiki link.

Written by the indexing model from the issue text.