Document .NET Tool packaging breaking change for .NET 10 Preview 6

[Copilot]

This PR documents the breaking change where .NET Tool packaging now invokes Publish instead of Build, affecting which assets are included in tool packages.

What changed

In .NET 10 Preview 6, the .NET Tool packaging process changed from invoking the Build target to the Publish target. This means that assets created during the publish process (like StaticWebAssets from WebSDK, minified and trimmed application assets) are now included in tool packages by default.

Impact

• Users who previously copied these files explicitly may receive build diagnostics warning them of duplicate copies
• Tool packages will now include publish-time optimizations automatically
• Enables creation of optimized, platform-specific .NET Tool packages (self-contained tools, trimmed/AOT tools)

Documentation added

• New file: docs/core/compatibility/sdk/10.0/dotnet-tool-pack-publish.md - Complete breaking change documentation following established patterns
• Updated: docs/core/compatibility/toc.yml - Added entry to SDK section
• Updated: docs/core/compatibility/10.0.md - Added entry to SDK breaking changes table

The documentation follows the Microsoft Writing Style Guide and includes all required sections: version information, previous/new behavior, type of breaking change, reason for change, recommended actions, and affected APIs.

Fixes #47916.

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Internal previews

📄 File	🔗 Preview link
docs/core/compatibility/10.0.md	Breaking changes in .NET 10
docs/core/compatibility/sdk/10.0/dotnet-tool-pack-publish.md	.NET tool packaging invokes Publish instead of Build
docs/core/compatibility/toc.yml	docs/core/compatibility/toc

[BillWagner]

This LGTM. I had one technical question to resolve before merging.