Adding documentation for CA1516 - Use cross-platform intrinsics

[tannergooding]

This is the docs side change for dotnet/roslyn-analyzers#7721

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Internal previews

📄 File	🔗 Preview link
docs/fundamentals/code-analysis/code-quality-rule-options.md	Code quality rule configuration options
docs/fundamentals/code-analysis/quality-rules/ca1516.md	CA1516: Use cross-platform intrinsics
docs/fundamentals/code-analysis/quality-rules/index.md	Code quality rules overview
docs/fundamentals/code-analysis/quality-rules/maintainability-warnings.md	Maintainability rules
docs/navigate/tools-diagnostics/toc.yml	docs/navigate/tools-diagnostics/toc

[gewarren]

Thanks @tannergooding. Can you add it the new rule to the various index and TOC files (you can see an example here)? Also, can you add CA1516 to the output_kind option table?

[tannergooding]

@gewarren, done!

Still waiting on the actual analyzer to finish being reviewed and merged.

[tannergooding]

Analyzer was merged, so this should be good to merge as well now