Add documentation for CA2026: Prefer JsonElement.Parse over JsonDocument.Parse().RootElement

[Copilot]

Adds missing documentation for CA2026, a .NET 10 performance analyzer that flags inefficient JSON parsing patterns.

Changes

• New rule documentation (ca2026.md): Explains why JsonElement.Parse() is preferred over JsonDocument.Parse().RootElement in .NET 10+
  • JsonDocument implements IDisposable and rents from ArrayPool<byte>, requiring disposal to avoid memory leaks
  • JsonElement.Parse() parses directly without allocation overhead or disposal requirements
• Index updates: Added CA2026 entries to performance-warnings.md and index.md
• External code snippets: Created compilable C# and VB code examples in snippets/csharp/all-rules/ca2026.cs and snippets/vb/all-rules/ca2026.vb
  • Uses conditional compilation to handle .NET 10 API availability
  • Both projects compile successfully with existing all-rules projects

Example

// Violation: Creates disposable JsonDocument, rents from ArrayPool
JsonElement element = JsonDocument.Parse(json).RootElement;

// Fixed: Direct parse, no disposal needed
JsonElement element = JsonElement.Parse(json);

Closes #49504

Original prompt

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This section details on the original issue you should resolve

<issue_title>Add doc for CA2026</issue_title>
<issue_description>CA2026: Prefer JsonElement.Parse over JsonDocument.Parse().RootElement is also missing documentation.

Originally posted by @xtqqczze in #49492 (comment)

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Associated WorkItem - 505743</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add doc for CA2026 #49504

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Internal previews

📄 File	🔗 Preview link
docs/fundamentals/code-analysis/quality-rules/ca2026.md	CA2026: Prefer JsonElement.Parse over JsonDocument.Parse().RootElement
docs/fundamentals/code-analysis/quality-rules/index.md	Code quality rules overview
docs/fundamentals/code-analysis/quality-rules/reliability-warnings.md	Reliability rules
docs/navigate/tools-diagnostics/toc.yml	docs/navigate/tools-diagnostics/toc

[Copilot]

Pull Request Overview

This pull request adds documentation for a new code analysis rule CA2026, which recommends using JsonElement.Parse() instead of JsonDocument.Parse().RootElement for better performance and resource management in .NET 10.

Key changes:

• Adds complete documentation for CA2026 rule with C# and VB examples.
• Updates the table of contents, rule index, and reliability warnings list to include CA2026.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
docs/fundamentals/code-analysis/quality-rules/ca2026.md	New documentation file for CA2026 rule with examples and guidance
docs/navigate/tools-diagnostics/toc.yml	Adds CA2026 to the navigation table of contents
docs/fundamentals/code-analysis/quality-rules/reliability-warnings.md	Adds CA2026 to the reliability warnings table
docs/fundamentals/code-analysis/quality-rules/index.md	Adds CA2026 to the main quality rules index

Comments suppressed due to low confidence (1)

docs/fundamentals/code-analysis/quality-rules/ca2026.md:1

• The ms.topic: reference metadata field is missing from the frontmatter. This field is present in similar rule documentation files (like ca2024.md and ca2025.md) and should be included for consistency.

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[BillWagner]

Overall, this looks great. One comment.