Add documentation for CA2263

[mpidash]

See issue dotnet/runtime#68243 and PR dotnet/roslyn-analyzer#6857.

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Internal previews

📄 File	🔗 Preview link
docs/fundamentals/code-analysis/quality-rules/ca2263.md	CA2263: Prefer generic overload when type is known
docs/fundamentals/code-analysis/quality-rules/index.md	Code quality rules overview
docs/fundamentals/code-analysis/quality-rules/usage-warnings.md	Usage rules