Breaking change docs: CborReader/CborWriter enforce default maximum nesting depth (.NET 11)

[Copilot]

Documents the .NET 11 Preview 5 breaking change where CborReader and CborWriter now enforce maximum nesting depths by default (64 and 1000, respectively), throwing CborContentException and InvalidOperationException when exceeded.

Changes

• New article docs/core/compatibility/core-libraries/11/cbor-max-depth.md — covers previous/new behavior, affected APIs, and how to configure a higher limit via the new CborReaderOptions/CborWriterOptions types
• docs/core/compatibility/11.md — adds entry under Core .NET libraries
• docs/core/compatibility/toc.yml — adds entry under .NET 11 Core .NET libraries
• Article updates — uses xrefs for the first mentions of CborReader and CborWriter, and refines the rationale wording to match repo style guidance

Key callout documented

Unlike Utf8JsonReader/Utf8JsonWriter, MaxDepth = 0 means no nesting allowed (not "use the runtime default"). Users who need deeper nesting must opt in explicitly:

var options = new CborReaderOptions { MaxDepth = 256 };
var reader = new CborReader(data, options);

var writerOptions = new CborWriterOptions { MaxDepth = 2000 };
var writer = new CborWriter(writerOptions);

You cannot use an AppContext switch to restore the previous unlimited-depth behavior.

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Internal previews

📄 File	🔗 Preview link
docs/core/compatibility/11.md	Breaking changes in .NET 11
docs/core/compatibility/core-libraries/11/cbor-max-depth.md	CborReader and CborWriter enforce a default maximum nesting depth
docs/core/compatibility/toc.yml	docs/core/compatibility/toc

[Copilot]

Pull request overview

Documents a .NET 11 Preview 5 breaking change in System.Formats.Cbor where CborReader and CborWriter now enforce default maximum nesting depths, and explains how to configure higher limits with the new options types.

Changes:

• Adds a new breaking-change article describing previous vs. new max-depth behavior, exceptions thrown, and mitigation via CborReaderOptions/CborWriterOptions.
• Adds the new breaking change to the .NET 11 compatibility index page under Extensions.
• Adds the new article to the compatibility TOC under .NET 11 > Extensions.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
docs/core/compatibility/extensions/11/cbor-max-depth.md	New breaking-change article documenting default max depth enforcement and configuration guidance.
docs/core/compatibility/11.md	Adds the new breaking change entry to the .NET 11 list under Extensions.
docs/core/compatibility/toc.yml	Adds TOC navigation entry for the new .NET 11 Extensions breaking change article.

[BillWagner]

This LGTM. Let's