add steps to write modulewithloss wrapper (#16486)
### Description
This PR includes documentation updates, providing step-by-step
instructions on how to implement the ModuleWithLoss wrapper in a
different codebase.
The documentation outlines the necessary code changes and offers
customization options based on specific requirements.
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Co-authored-by: Adam Louly <adamlouly@microsoft.com@orttrainingdev9.d32nl1ml4oruzj4qz3bqlggovf.px.internal.cloudapp.net>
