Fix V10 Release Notes: Add Scheduled Messaging, Default Mappers, and Missing Feature Documentation

[Copilot]

The V10 release notes were missing documentation for several major features and changes. This PR comprehensively updates the release notes to include:

Major Missing Features Added

Scheduled Messaging - Documented the new scheduling capability (PR #3487) that allows sending messages at specific times or after delays:

// Schedule a command to be sent at a specific time
await commandProcessor.SendAt(new MyCommand(), DateTime.UtcNow.AddHours(1));

// Schedule an event to be published after a delay  
await commandProcessor.PublishAt(new MyEvent(), TimeSpan.FromMinutes(30));

Default Message Mappers - Added clarification that explicit message mappers aren't always required. Users can rely on default mappers (JsonMapper, CloudEventsMapper) unless they need explicit transforms, addressing a key point of confusion.

Enhanced Documentation

• Circuit Breaking: Enhanced with bulk dispatch support (PR feat: bulk dispatch to support circuit breaking #3688) and MongoDB integration (PR feat: Add support to tripped topics for MongoDB #3692)
• Polly Resilience Pipeline: Added configuration examples and CancellationToken integration details (PR fix: Use CancellationToken from ResiliencePipeline #3698)
• Request Context: Better documentation of partition key and header support (PR feat: Add support to set partition key and headers via Request Context #3678) with code examples
• OpenTelemetry: Comprehensive coverage including inbox tracing (PR Add OTel to persistent Inbox implementations #3576) and instrumentation control (PR Enforcing the InstrumentationOption on all Tracer Operations #3620)
• Transport Improvements: Added PostgreSQL message broker (PR Add support to PostgreSQL as message broker #3612), RabbitMQ enhancements, Kafka improvements
• Performance: Documented source-generated logging (PR feature: Use source generated logging #3579), GUID v7 (PR feat: Use GUID v7 for .NET 9+ #3687), and memory optimizations

Additional Improvements

• Added references to 20+ V10 PRs that were previously undocumented
• Enhanced breaking changes section with test framework and mapper guidance
• Documented bug fixes including outbox sweeper (PR fix: NullReference with outbox sweeper #3683) and Cloud Events unwrapping (PR fix: Unwrap Cloudevent #3686)
• Added developer experience improvements including enhanced test infrastructure (PR Improve test by adding colorful output and GHA logger #3635)

The release notes now provide complete coverage of V10 changes with proper PR references, code examples, and migration guidance for all major features.

Fixes #3704.

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