Add sub-section about Dotfuscator to Unity docs

[ghost]

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[msftclas]

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[saldana]

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File	Status	Preview URL	Details
docs/cross-platform/using-visual-studio-tools-for-unity.md	✅Succeeded
docs/cross-platform/visual-studio-tools-for-unity.md	✅Succeeded

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[TerryGLee]

FYI: I am checking in with the Unity PMs before we accept this PR.

[truist]

@TerryGLee thank you for your help with this. If there's anything we can do to help, please don't hesitate to contact me.

In case you're not familiar with Dotfuscator, our "Community Edition" (CE) has been packaged with Visual Studio (and in the Visual Studio docs) for years and is available through our website as a free download. We have been working on expanding the feature set of CE, recently adding Xamarin support (with a similar section in the Xamarin docs), and now with our latest release(s) we are adding Unity support.

We've seen a lot of recent interest in Unity protection, so this PR is meant to help Unity users discover that Dotfuscator is built into their existing toolset.