Create How-To Documentation For Dwell in MRTK3

[AMollis]

This issue has been migrated a new MRTK repository, and the status of this issue will now be tracked at the following location:

• Create How-To Documentation For Dwell in MRTK3 MixedRealityToolkit/MixedRealityToolkit-Unity#161

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Overview

MRTK2 provided a how-to document for adding dwell to an application, https://learn.microsoft.com/en-us/windows/mixed-reality/mrtk-unity/mrtk2/features/ux-building-blocks/dwell?view=mrtkunity-2022-05. We are missing a similar document for MRTK3.

Additional Context

There is already a reference API document for MRTK3's InteractorDwellManager

https://learn.microsoft.com/en-us/dotnet/api/microsoft.mixedreality.toolkit.input.interactordwellmanager?view=mrtkinput-3.0

[marlenaklein-msft]

Dwell info found here.